diff --git a/qa/pull-tester/rpc-tests.py b/qa/pull-tester/rpc-tests.py
index d794dbe80..6d3bda10e 100755
--- a/qa/pull-tester/rpc-tests.py
+++ b/qa/pull-tester/rpc-tests.py
@@ -32,13 +32,13 @@ import re
 from tests_config import *
 
 #If imported values are not defined then set to zero (or disabled)
-if not vars().has_key('ENABLE_WALLET'):
+if 'ENABLE_WALLET' not in vars():
     ENABLE_WALLET=0
-if not vars().has_key('ENABLE_BITCOIND'):
+if 'ENABLE_BITCOIND' not in vars():
     ENABLE_BITCOIND=0
-if not vars().has_key('ENABLE_UTILS'):
+if 'ENABLE_UTILS' not in vars():
     ENABLE_UTILS=0
-if not vars().has_key('ENABLE_ZMQ'):
+if 'ENABLE_ZMQ' not in vars():
     ENABLE_ZMQ=0
     
 # python-zmq may not be installed. Handle this gracefully and with some helpful info
diff --git a/qa/rpc-tests/bip65-cltv-p2p.py b/qa/rpc-tests/bip65-cltv-p2p.py
index bbd518cf5..54559c354 100755
--- a/qa/rpc-tests/bip65-cltv-p2p.py
+++ b/qa/rpc-tests/bip65-cltv-p2p.py
@@ -11,7 +11,7 @@ from test_framework.blocktools import create_coinbase, create_block
 from test_framework.comptool import TestInstance, TestManager
 from test_framework.script import CScript, OP_1NEGATE, OP_CHECKLOCKTIMEVERIFY, OP_DROP
 from binascii import unhexlify
-import cStringIO
+from io import BytesIO
 import time
 
 def cltv_invalidate(tx):
@@ -60,7 +60,7 @@ class BIP65Test(ComparisonTestFramework):
         rawtx = node.createrawtransaction(inputs, outputs)
         signresult = node.signrawtransaction(rawtx)
         tx = CTransaction()
-        f = cStringIO.StringIO(unhexlify(signresult['hex']))
+        f = BytesIO(unhexlify(signresult['hex']))
         tx.deserialize(f)
         return tx
 
@@ -70,7 +70,7 @@ class BIP65Test(ComparisonTestFramework):
         height = 3  # height of the next block to build
         self.tip = int ("0x" + self.nodes[0].getbestblockhash() + "L", 0)
         self.nodeaddress = self.nodes[0].getnewaddress()
-        self.last_block_time = time.time()
+        self.last_block_time = int(time.time())
 
         ''' 98 more version 3 blocks '''
         test_blocks = []
diff --git a/qa/rpc-tests/bip68-112-113-p2p.py b/qa/rpc-tests/bip68-112-113-p2p.py
index 7d3c59be3..f391cb0b7 100755
--- a/qa/rpc-tests/bip68-112-113-p2p.py
+++ b/qa/rpc-tests/bip68-112-113-p2p.py
@@ -11,7 +11,7 @@ from test_framework.blocktools import create_coinbase, create_block
 from test_framework.comptool import TestInstance, TestManager
 from test_framework.script import *
 from binascii import unhexlify
-import cStringIO
+from io import BytesIO
 import time
 
 '''
@@ -119,7 +119,7 @@ class BIP68_112_113Test(ComparisonTestFramework):
         outputs = { to_address : amount }
         rawtx = node.createrawtransaction(inputs, outputs)
         tx = CTransaction()
-        f = cStringIO.StringIO(unhexlify(rawtx))
+        f = BytesIO(unhexlify(rawtx))
         tx.deserialize(f)
         return tx
 
@@ -127,7 +127,7 @@ class BIP68_112_113Test(ComparisonTestFramework):
         rawtx = ToHex(unsignedtx)
         signresult = node.signrawtransaction(rawtx)
         tx = CTransaction()
-        f = cStringIO.StringIO(unhexlify(signresult['hex']))
+        f = BytesIO(unhexlify(signresult['hex']))
         tx.deserialize(f)
         return tx
 
diff --git a/qa/rpc-tests/bip68-sequence.py b/qa/rpc-tests/bip68-sequence.py
index 84f941da3..377a35b68 100755
--- a/qa/rpc-tests/bip68-sequence.py
+++ b/qa/rpc-tests/bip68-sequence.py
@@ -61,7 +61,7 @@ class BIP68Test(BitcoinTestFramework):
         utxo = utxos[0]
 
         tx1 = CTransaction()
-        value = satoshi_round(utxo["amount"] - self.relayfee)*COIN
+        value = int(satoshi_round(utxo["amount"] - self.relayfee)*COIN)
 
         # Check that the disable flag disables relative locktime.
         # If sequence locks were used, this would require 1 block for the
@@ -179,8 +179,8 @@ class BIP68Test(BitcoinTestFramework):
                 tx.vin.append(CTxIn(COutPoint(int(utxos[j]["txid"], 16), utxos[j]["vout"]), nSequence=sequence_value))
                 value += utxos[j]["amount"]*COIN
             # Overestimate the size of the tx - signatures should be less than 120 bytes, and leave 50 for the output
-            tx_size = len(ToHex(tx))/2 + 120*num_inputs + 50
-            tx.vout.append(CTxOut(value-self.relayfee*tx_size*COIN/1000, CScript([b'a'])))
+            tx_size = len(ToHex(tx))//2 + 120*num_inputs + 50
+            tx.vout.append(CTxOut(int(value-self.relayfee*tx_size*COIN/1000), CScript([b'a'])))
             rawtx = self.nodes[0].signrawtransaction(ToHex(tx))["hex"]
 
             try:
diff --git a/qa/rpc-tests/bip9-softforks.py b/qa/rpc-tests/bip9-softforks.py
index cbb1b7d4c..98975e719 100755
--- a/qa/rpc-tests/bip9-softforks.py
+++ b/qa/rpc-tests/bip9-softforks.py
@@ -11,7 +11,7 @@ from test_framework.blocktools import create_coinbase, create_block
 from test_framework.comptool import TestInstance, TestManager
 from test_framework.script import CScript, OP_1NEGATE, OP_NOP3, OP_DROP
 from binascii import hexlify, unhexlify
-import cStringIO
+from io import BytesIO
 import time
 import itertools
 
@@ -53,7 +53,7 @@ class BIP9SoftForksTest(ComparisonTestFramework):
         outputs = { to_address : amount }
         rawtx = node.createrawtransaction(inputs, outputs)
         tx = CTransaction()
-        f = cStringIO.StringIO(unhexlify(rawtx))
+        f = BytesIO(unhexlify(rawtx))
         tx.deserialize(f)
         tx.nVersion = 2
         return tx
@@ -61,7 +61,7 @@ class BIP9SoftForksTest(ComparisonTestFramework):
     def sign_transaction(self, node, tx):
         signresult = node.signrawtransaction(hexlify(tx.serialize()))
         tx = CTransaction()
-        f = cStringIO.StringIO(unhexlify(signresult['hex']))
+        f = BytesIO(unhexlify(signresult['hex']))
         tx.deserialize(f)
         return tx
 
@@ -91,7 +91,7 @@ class BIP9SoftForksTest(ComparisonTestFramework):
         self.height = 3  # height of the next block to build
         self.tip = int ("0x" + self.nodes[0].getbestblockhash() + "L", 0)
         self.nodeaddress = self.nodes[0].getnewaddress()
-        self.last_block_time = time.time()
+        self.last_block_time = int(time.time())
 
         assert_equal(self.get_bip9_status(bipName)['status'], 'defined')
 
@@ -217,4 +217,4 @@ class BIP9SoftForksTest(ComparisonTestFramework):
         tx.nLockTime = self.last_block_time
 
 if __name__ == '__main__':
-    BIP9SoftForksTest().main()
\ No newline at end of file
+    BIP9SoftForksTest().main()
diff --git a/qa/rpc-tests/bipdersig-p2p.py b/qa/rpc-tests/bipdersig-p2p.py
index 544e4a967..95be385d9 100755
--- a/qa/rpc-tests/bipdersig-p2p.py
+++ b/qa/rpc-tests/bipdersig-p2p.py
@@ -11,7 +11,7 @@ from test_framework.blocktools import create_coinbase, create_block
 from test_framework.comptool import TestInstance, TestManager
 from test_framework.script import CScript
 from binascii import unhexlify
-import cStringIO
+from io import BytesIO
 import time
 
 # A canonical signature consists of: 
@@ -68,7 +68,7 @@ class BIP66Test(ComparisonTestFramework):
         rawtx = node.createrawtransaction(inputs, outputs)
         signresult = node.signrawtransaction(rawtx)
         tx = CTransaction()
-        f = cStringIO.StringIO(unhexlify(signresult['hex']))
+        f = BytesIO(unhexlify(signresult['hex']))
         tx.deserialize(f)
         return tx
 
@@ -78,7 +78,7 @@ class BIP66Test(ComparisonTestFramework):
         height = 3  # height of the next block to build
         self.tip = int ("0x" + self.nodes[0].getbestblockhash() + "L", 0)
         self.nodeaddress = self.nodes[0].getnewaddress()
-        self.last_block_time = time.time()
+        self.last_block_time = int(time.time())
 
         ''' 98 more version 2 blocks '''
         test_blocks = []
diff --git a/qa/rpc-tests/decodescript.py b/qa/rpc-tests/decodescript.py
index 490808d49..2dfafac2f 100755
--- a/qa/rpc-tests/decodescript.py
+++ b/qa/rpc-tests/decodescript.py
@@ -7,7 +7,7 @@ from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import *
 from test_framework.mininode import *
 from binascii import hexlify, unhexlify
-from cStringIO import StringIO
+from io import BytesIO
 
 class DecodeScriptTest(BitcoinTestFramework):
     """Tests decoding scripts via RPC command "decodescript"."""
@@ -131,7 +131,7 @@ class DecodeScriptTest(BitcoinTestFramework):
         assert_equal('OP_DUP OP_HASH160 dc863734a218bfe83ef770ee9d41a27f824a6e56 OP_EQUALVERIFY OP_CHECKSIG', rpc_result['vout'][0]['scriptPubKey']['asm'])
         assert_equal('OP_HASH160 2a5edea39971049a540474c6a99edf0aa4074c58 OP_EQUAL', rpc_result['vout'][1]['scriptPubKey']['asm'])
         txSave = CTransaction()
-        txSave.deserialize(StringIO(unhexlify(tx)))
+        txSave.deserialize(BytesIO(unhexlify(tx)))
 
         # make sure that a specifically crafted op_return value will not pass all the IsDERSignature checks and then get decoded as a sighash type
         tx = '01000000015ded05872fdbda629c7d3d02b194763ce3b9b1535ea884e3c8e765d42e316724020000006b48304502204c10d4064885c42638cbff3585915b322de33762598321145ba033fc796971e2022100bb153ad3baa8b757e30a2175bd32852d2e1cb9080f84d7e32fcdfd667934ef1b012103163c0ff73511ea1743fb5b98384a2ff09dd06949488028fd819f4d83f56264efffffffff0200000000000000000b6a0930060201000201000180380100000000001976a9141cabd296e753837c086da7a45a6c2fe0d49d7b7b88ac00000000'
diff --git a/qa/rpc-tests/disablewallet.py b/qa/rpc-tests/disablewallet.py
index 5af815846..cb868029f 100755
--- a/qa/rpc-tests/disablewallet.py
+++ b/qa/rpc-tests/disablewallet.py
@@ -32,7 +32,7 @@ class DisableWalletTest (BitcoinTestFramework):
         # Checking mining to an address without a wallet
         try:
             self.nodes[0].generatetoaddress(1, 'mneYUmWYsuk7kySiURxCi3AGxrAqZxLgPZ')
-        except JSONRPCException,e:
+        except JSONRPCException as e:
             assert("Invalid address" not in e.error['message'])
             assert("ProcessNewBlock, block not accepted" not in e.error['message'])
             assert("Couldn't create new block" not in e.error['message'])
@@ -40,7 +40,7 @@ class DisableWalletTest (BitcoinTestFramework):
         try:
             self.nodes[0].generatetoaddress(1, '3J98t1WpEZ73CNmQviecrnyiWrnqRhWNLy')
             raise AssertionError("Must not mine to invalid address!")
-        except JSONRPCException,e:
+        except JSONRPCException as e:
             assert("Invalid address" in e.error['message'])
 
 if __name__ == '__main__':
diff --git a/qa/rpc-tests/fundrawtransaction.py b/qa/rpc-tests/fundrawtransaction.py
index 445871281..82c9e48a4 100755
--- a/qa/rpc-tests/fundrawtransaction.py
+++ b/qa/rpc-tests/fundrawtransaction.py
@@ -48,7 +48,7 @@ class RawTransactionsTest(BitcoinTestFramework):
 
         watchonly_address = self.nodes[0].getnewaddress()
         watchonly_pubkey = self.nodes[0].validateaddress(watchonly_address)["pubkey"]
-        watchonly_amount = 200
+        watchonly_amount = Decimal(200)
         self.nodes[3].importpubkey(watchonly_pubkey, "", True)
         watchonly_txid = self.nodes[0].sendtoaddress(watchonly_address, watchonly_amount)
         self.nodes[0].sendtoaddress(self.nodes[3].getnewaddress(), watchonly_amount / 10)
@@ -209,7 +209,7 @@ class RawTransactionsTest(BitcoinTestFramework):
         matchingOuts = 0
         for i, out in enumerate(dec_tx['vout']):
             totalOut += out['value']
-            if outputs.has_key(out['scriptPubKey']['addresses'][0]):
+            if out['scriptPubKey']['addresses'][0] in outputs:
                 matchingOuts+=1
             else:
                 assert_equal(i, rawtxfund['changepos'])
@@ -249,7 +249,7 @@ class RawTransactionsTest(BitcoinTestFramework):
         matchingOuts = 0
         for out in dec_tx['vout']:
             totalOut += out['value']
-            if outputs.has_key(out['scriptPubKey']['addresses'][0]):
+            if out['scriptPubKey']['addresses'][0] in outputs:
                 matchingOuts+=1
 
         assert_equal(matchingOuts, 1)
@@ -291,7 +291,7 @@ class RawTransactionsTest(BitcoinTestFramework):
         matchingOuts = 0
         for out in dec_tx['vout']:
             totalOut += out['value']
-            if outputs.has_key(out['scriptPubKey']['addresses'][0]):
+            if out['scriptPubKey']['addresses'][0] in outputs:
                 matchingOuts+=1
 
         assert_equal(matchingOuts, 2)
@@ -309,7 +309,7 @@ class RawTransactionsTest(BitcoinTestFramework):
         try:
             rawtxfund = self.nodes[2].fundrawtransaction(rawtx)
             raise AssertionError("Spent more than available")
-        except JSONRPCException,e:
+        except JSONRPCException as e:
             assert("Insufficient" in e.error['message'])
 
 
diff --git a/qa/rpc-tests/importprunedfunds.py b/qa/rpc-tests/importprunedfunds.py
index 5cbdcde9a..db875800d 100755
--- a/qa/rpc-tests/importprunedfunds.py
+++ b/qa/rpc-tests/importprunedfunds.py
@@ -82,7 +82,7 @@ class ImportPrunedFundsTest(BitcoinTestFramework):
         #Import with no affiliated address
         try:
             result1 = self.nodes[1].importprunedfunds(rawtxn1, proof1, "")
-        except JSONRPCException,e:
+        except JSONRPCException as e:
             errorString = e.error['message']
 
         assert('No addresses' in errorString)
@@ -119,7 +119,7 @@ class ImportPrunedFundsTest(BitcoinTestFramework):
 
         try:
             self.nodes[1].removeprunedfunds(txnid1)
-        except JSONRPCException,e:
+        except JSONRPCException as e:
             errorString = e.error['message']
 
         assert('does not exist' in errorString)
diff --git a/qa/rpc-tests/keypool.py b/qa/rpc-tests/keypool.py
index 95d0d6832..5253d49c3 100755
--- a/qa/rpc-tests/keypool.py
+++ b/qa/rpc-tests/keypool.py
@@ -46,7 +46,7 @@ class KeyPoolTest(BitcoinTestFramework):
         try:
             addr = nodes[0].getnewaddress()
             raise AssertionError('Keypool should be exhausted after one address')
-        except JSONRPCException,e:
+        except JSONRPCException as e:
             assert(e.error['code']==-12)
 
         # put three new keys in the keypool
@@ -66,7 +66,7 @@ class KeyPoolTest(BitcoinTestFramework):
         try:
             addr = nodes[0].getrawchangeaddress()
             raise AssertionError('Keypool should be exhausted after three addresses')
-        except JSONRPCException,e:
+        except JSONRPCException as e:
             assert(e.error['code']==-12)
 
         # refill keypool with three new addresses
@@ -84,7 +84,7 @@ class KeyPoolTest(BitcoinTestFramework):
         try:
             nodes[0].generate(1)
             raise AssertionError('Keypool should be exhausted after three addesses')
-        except JSONRPCException,e:
+        except JSONRPCException as e:
             assert(e.error['code']==-12)
 
     def setup_chain(self):
diff --git a/qa/rpc-tests/listtransactions.py b/qa/rpc-tests/listtransactions.py
index da1e98dc3..8fe72d95d 100755
--- a/qa/rpc-tests/listtransactions.py
+++ b/qa/rpc-tests/listtransactions.py
@@ -8,12 +8,12 @@
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import *
 from test_framework.mininode import CTransaction, COIN
-import cStringIO
+from io import BytesIO
 import binascii
 
 def txFromHex(hexstring):
     tx = CTransaction()
-    f = cStringIO.StringIO(binascii.unhexlify(hexstring))
+    f = BytesIO(binascii.unhexlify(hexstring))
     tx.deserialize(f)
     return tx
 
@@ -192,7 +192,7 @@ class ListTransactionsTest(BitcoinTestFramework):
 
         # Replace tx3, and check that tx4 becomes unknown
         tx3_b = tx3_modified
-        tx3_b.vout[0].nValue -= 0.004 * COIN # bump the fee
+        tx3_b.vout[0].nValue -= int(Decimal("0.004") * COIN) # bump the fee
         tx3_b = binascii.hexlify(tx3_b.serialize()).decode('utf-8')
         tx3_b_signed = self.nodes[0].signrawtransaction(tx3_b)['hex']
         txid_3b = self.nodes[0].sendrawtransaction(tx3_b_signed, True)
diff --git a/qa/rpc-tests/maxuploadtarget.py b/qa/rpc-tests/maxuploadtarget.py
index e4127500c..be45fecb5 100755
--- a/qa/rpc-tests/maxuploadtarget.py
+++ b/qa/rpc-tests/maxuploadtarget.py
@@ -177,7 +177,7 @@ class MaxUploadTest(BitcoinTestFramework):
         max_bytes_per_day = 200*1024*1024
         daily_buffer = 144 * MAX_BLOCK_SIZE
         max_bytes_available = max_bytes_per_day - daily_buffer
-        success_count = max_bytes_available / old_block_size
+        success_count = max_bytes_available // old_block_size
 
         # 144MB will be reserved for relaying new blocks, so expect this to
         # succeed for ~70 tries.
diff --git a/qa/rpc-tests/p2p-acceptblock.py b/qa/rpc-tests/p2p-acceptblock.py
index bf355780c..e429fcc5f 100755
--- a/qa/rpc-tests/p2p-acceptblock.py
+++ b/qa/rpc-tests/p2p-acceptblock.py
@@ -150,7 +150,7 @@ class AcceptBlockTest(BitcoinTestFramework):
         # 2. Send one block that builds on each tip.
         # This should be accepted.
         blocks_h2 = []  # the height 2 blocks on each node's chain
-        block_time = time.time() + 1
+        block_time = int(time.time()) + 1
         for i in xrange(2):
             blocks_h2.append(create_block(tips[i], create_coinbase(2), block_time))
             blocks_h2[i].solve()
diff --git a/qa/rpc-tests/p2p-fullblocktest.py b/qa/rpc-tests/p2p-fullblocktest.py
index b1e8ca53e..131350c98 100755
--- a/qa/rpc-tests/p2p-fullblocktest.py
+++ b/qa/rpc-tests/p2p-fullblocktest.py
@@ -269,7 +269,7 @@ class FullBlockTest(ComparisonTestFramework):
         #                      \-> b3 (1) -> b4 (2)
         
         # Test that a block with a lot of checksigs is okay
-        lots_of_checksigs = CScript([OP_CHECKSIG] * (1000000 / 50 - 1))
+        lots_of_checksigs = CScript([OP_CHECKSIG] * (1000000 // 50 - 1))
         tip(13)
         block(15, spend=out5, script=lots_of_checksigs)
         yield accepted()
@@ -277,7 +277,7 @@ class FullBlockTest(ComparisonTestFramework):
 
         # Test that a block with too many checksigs is rejected
         out6 = get_spendable_output()
-        too_many_checksigs = CScript([OP_CHECKSIG] * (1000000 / 50))
+        too_many_checksigs = CScript([OP_CHECKSIG] * (1000000 // 50))
         block(16, spend=out6, script=too_many_checksigs)
         yield rejected(RejectResult(16, 'bad-blk-sigops'))
 
diff --git a/qa/rpc-tests/pruning.py b/qa/rpc-tests/pruning.py
index b0f4b88ae..dd2adea95 100755
--- a/qa/rpc-tests/pruning.py
+++ b/qa/rpc-tests/pruning.py
@@ -15,7 +15,7 @@ from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import *
 
 def calc_usage(blockdir):
-    return sum(os.path.getsize(blockdir+f) for f in os.listdir(blockdir) if os.path.isfile(blockdir+f))/(1024*1024)
+    return sum(os.path.getsize(blockdir+f) for f in os.listdir(blockdir) if os.path.isfile(blockdir+f)) / (1024. * 1024.)
 
 class PruneTest(BitcoinTestFramework):
 
@@ -56,7 +56,7 @@ class PruneTest(BitcoinTestFramework):
         self.nodes[1].generate(200)
         sync_blocks(self.nodes[0:2])
         self.nodes[0].generate(150)
-        # Then mine enough full blocks to create more than 550MB of data
+        # Then mine enough full blocks to create more than 550MiB of data
         for i in xrange(645):
             self.mine_full_block(self.nodes[0], self.address[0])
 
@@ -66,7 +66,7 @@ class PruneTest(BitcoinTestFramework):
         if not os.path.isfile(self.prunedir+"blk00000.dat"):
             raise AssertionError("blk00000.dat is missing, pruning too early")
         print "Success"
-        print "Though we're already using more than 550MB, current usage:", calc_usage(self.prunedir)
+        print "Though we're already using more than 550MiB, current usage:", calc_usage(self.prunedir)
         print "Mining 25 more blocks should cause the first block file to be pruned"
         # Pruning doesn't run until we're allocating another chunk, 20 full blocks past the height cutoff will ensure this
         for i in xrange(25):
diff --git a/qa/rpc-tests/rawtransactions.py b/qa/rpc-tests/rawtransactions.py
index dd9e5e28a..9f660c8bd 100755
--- a/qa/rpc-tests/rawtransactions.py
+++ b/qa/rpc-tests/rawtransactions.py
@@ -59,7 +59,7 @@ class RawTransactionsTest(BitcoinTestFramework):
         errorString = ""
         try:
             rawtx   = self.nodes[2].sendrawtransaction(rawtx['hex'])
-        except JSONRPCException,e:
+        except JSONRPCException as e:
             errorString = e.error['message']
 
         assert("Missing inputs" in errorString)
diff --git a/qa/rpc-tests/replace-by-fee.py b/qa/rpc-tests/replace-by-fee.py
index eded24f40..b951900c4 100755
--- a/qa/rpc-tests/replace-by-fee.py
+++ b/qa/rpc-tests/replace-by-fee.py
@@ -119,7 +119,7 @@ class ReplaceByFeeTest(BitcoinTestFramework):
 
     def test_simple_doublespend(self):
         """Simple doublespend"""
-        tx0_outpoint = make_utxo(self.nodes[0], 1.1*COIN)
+        tx0_outpoint = make_utxo(self.nodes[0], int(1.1*COIN))
 
         tx1a = CTransaction()
         tx1a.vin = [CTxIn(tx0_outpoint, nSequence=0)]
@@ -143,7 +143,7 @@ class ReplaceByFeeTest(BitcoinTestFramework):
         # Extra 0.1 BTC fee
         tx1b = CTransaction()
         tx1b.vin = [CTxIn(tx0_outpoint, nSequence=0)]
-        tx1b.vout = [CTxOut(0.9*COIN, CScript([b'b']))]
+        tx1b.vout = [CTxOut(int(0.9*COIN), CScript([b'b']))]
         tx1b_hex = txToHex(tx1b)
         tx1b_txid = self.nodes[0].sendrawtransaction(tx1b_hex, True)
 
@@ -235,7 +235,7 @@ class ReplaceByFeeTest(BitcoinTestFramework):
                                   _total_txs=_total_txs):
                     yield x
 
-        fee = 0.0001*COIN
+        fee = int(0.0001*COIN)
         n = MAX_REPLACEMENT_LIMIT
         tree_txs = list(branch(tx0_outpoint, initial_nValue, n, fee=fee))
         assert_equal(len(tree_txs), n)
@@ -268,7 +268,7 @@ class ReplaceByFeeTest(BitcoinTestFramework):
         # Try again, but with more total transactions than the "max txs
         # double-spent at once" anti-DoS limit.
         for n in (MAX_REPLACEMENT_LIMIT+1, MAX_REPLACEMENT_LIMIT*2):
-            fee = 0.0001*COIN
+            fee = int(0.0001*COIN)
             tx0_outpoint = make_utxo(self.nodes[0], initial_nValue)
             tree_txs = list(branch(tx0_outpoint, initial_nValue, n, fee=fee))
             assert_equal(len(tree_txs), n)
@@ -291,7 +291,7 @@ class ReplaceByFeeTest(BitcoinTestFramework):
 
     def test_replacement_feeperkb(self):
         """Replacement requires fee-per-KB to be higher"""
-        tx0_outpoint = make_utxo(self.nodes[0], 1.1*COIN)
+        tx0_outpoint = make_utxo(self.nodes[0], int(1.1*COIN))
 
         tx1a = CTransaction()
         tx1a.vin = [CTxIn(tx0_outpoint, nSequence=0)]
@@ -303,7 +303,7 @@ class ReplaceByFeeTest(BitcoinTestFramework):
         # rejected.
         tx1b = CTransaction()
         tx1b.vin = [CTxIn(tx0_outpoint, nSequence=0)]
-        tx1b.vout = [CTxOut(0.001*COIN, CScript([b'a'*999000]))]
+        tx1b.vout = [CTxOut(int(0.001*COIN), CScript([b'a'*999000]))]
         tx1b_hex = txToHex(tx1b)
 
         try:
@@ -315,12 +315,12 @@ class ReplaceByFeeTest(BitcoinTestFramework):
 
     def test_spends_of_conflicting_outputs(self):
         """Replacements that spend conflicting tx outputs are rejected"""
-        utxo1 = make_utxo(self.nodes[0], 1.2*COIN)
-        utxo2 = make_utxo(self.nodes[0], 3.0*COIN)
+        utxo1 = make_utxo(self.nodes[0], int(1.2*COIN))
+        utxo2 = make_utxo(self.nodes[0], 3*COIN)
 
         tx1a = CTransaction()
         tx1a.vin = [CTxIn(utxo1, nSequence=0)]
-        tx1a.vout = [CTxOut(1.1*COIN, CScript([b'a']))]
+        tx1a.vout = [CTxOut(int(1.1*COIN), CScript([b'a']))]
         tx1a_hex = txToHex(tx1a)
         tx1a_txid = self.nodes[0].sendrawtransaction(tx1a_hex, True)
 
@@ -343,7 +343,7 @@ class ReplaceByFeeTest(BitcoinTestFramework):
         # Spend tx1a's output to test the indirect case.
         tx1b = CTransaction()
         tx1b.vin = [CTxIn(COutPoint(tx1a_txid, 0), nSequence=0)]
-        tx1b.vout = [CTxOut(1.0*COIN, CScript([b'a']))]
+        tx1b.vout = [CTxOut(1*COIN, CScript([b'a']))]
         tx1b_hex = txToHex(tx1b)
         tx1b_txid = self.nodes[0].sendrawtransaction(tx1b_hex, True)
         tx1b_txid = int(tx1b_txid, 16)
@@ -363,12 +363,12 @@ class ReplaceByFeeTest(BitcoinTestFramework):
 
     def test_new_unconfirmed_inputs(self):
         """Replacements that add new unconfirmed inputs are rejected"""
-        confirmed_utxo = make_utxo(self.nodes[0], 1.1*COIN)
-        unconfirmed_utxo = make_utxo(self.nodes[0], 0.1*COIN, False)
+        confirmed_utxo = make_utxo(self.nodes[0], int(1.1*COIN))
+        unconfirmed_utxo = make_utxo(self.nodes[0], int(0.1*COIN), False)
 
         tx1 = CTransaction()
         tx1.vin = [CTxIn(confirmed_utxo)]
-        tx1.vout = [CTxOut(1.0*COIN, CScript([b'a']))]
+        tx1.vout = [CTxOut(1*COIN, CScript([b'a']))]
         tx1_hex = txToHex(tx1)
         tx1_txid = self.nodes[0].sendrawtransaction(tx1_hex, True)
 
@@ -392,7 +392,7 @@ class ReplaceByFeeTest(BitcoinTestFramework):
         # Start by creating a single transaction with many outputs
         initial_nValue = 10*COIN
         utxo = make_utxo(self.nodes[0], initial_nValue)
-        fee = 0.0001*COIN
+        fee = int(0.0001*COIN)
         split_value = int((initial_nValue-fee)/(MAX_REPLACEMENT_LIMIT+1))
         actual_fee = initial_nValue - split_value*(MAX_REPLACEMENT_LIMIT+1)
 
@@ -445,7 +445,7 @@ class ReplaceByFeeTest(BitcoinTestFramework):
 
     def test_opt_in(self):
         """ Replacing should only work if orig tx opted in """
-        tx0_outpoint = make_utxo(self.nodes[0], 1.1*COIN)
+        tx0_outpoint = make_utxo(self.nodes[0], int(1.1*COIN))
 
         # Create a non-opting in transaction
         tx1a = CTransaction()
@@ -457,7 +457,7 @@ class ReplaceByFeeTest(BitcoinTestFramework):
         # Shouldn't be able to double-spend
         tx1b = CTransaction()
         tx1b.vin = [CTxIn(tx0_outpoint, nSequence=0)]
-        tx1b.vout = [CTxOut(0.9*COIN, CScript([b'b']))]
+        tx1b.vout = [CTxOut(int(0.9*COIN), CScript([b'b']))]
         tx1b_hex = txToHex(tx1b)
 
         try:
@@ -468,7 +468,7 @@ class ReplaceByFeeTest(BitcoinTestFramework):
             print tx1b_txid
             assert(False)
 
-        tx1_outpoint = make_utxo(self.nodes[0], 1.1*COIN)
+        tx1_outpoint = make_utxo(self.nodes[0], int(1.1*COIN))
 
         # Create a different non-opting in transaction
         tx2a = CTransaction()
@@ -480,7 +480,7 @@ class ReplaceByFeeTest(BitcoinTestFramework):
         # Still shouldn't be able to double-spend
         tx2b = CTransaction()
         tx2b.vin = [CTxIn(tx1_outpoint, nSequence=0)]
-        tx2b.vout = [CTxOut(0.9*COIN, CScript([b'b']))]
+        tx2b.vout = [CTxOut(int(0.9*COIN), CScript([b'b']))]
         tx2b_hex = txToHex(tx2b)
 
         try:
@@ -500,19 +500,19 @@ class ReplaceByFeeTest(BitcoinTestFramework):
         tx3a = CTransaction()
         tx3a.vin = [CTxIn(COutPoint(tx1a_txid, 0), nSequence=0xffffffff),
                     CTxIn(COutPoint(tx2a_txid, 0), nSequence=0xfffffffd)]
-        tx3a.vout = [CTxOut(0.9*COIN, CScript([b'c'])), CTxOut(0.9*COIN, CScript([b'd']))]
+        tx3a.vout = [CTxOut(int(0.9*COIN), CScript([b'c'])), CTxOut(int(0.9*COIN), CScript([b'd']))]
         tx3a_hex = txToHex(tx3a)
 
         self.nodes[0].sendrawtransaction(tx3a_hex, True)
 
         tx3b = CTransaction()
         tx3b.vin = [CTxIn(COutPoint(tx1a_txid, 0), nSequence=0)]
-        tx3b.vout = [CTxOut(0.5*COIN, CScript([b'e']))]
+        tx3b.vout = [CTxOut(int(0.5*COIN), CScript([b'e']))]
         tx3b_hex = txToHex(tx3b)
 
         tx3c = CTransaction()
         tx3c.vin = [CTxIn(COutPoint(tx2a_txid, 0), nSequence=0)]
-        tx3c.vout = [CTxOut(0.5*COIN, CScript([b'f']))]
+        tx3c.vout = [CTxOut(int(0.5*COIN), CScript([b'f']))]
         tx3c_hex = txToHex(tx3c)
 
         self.nodes[0].sendrawtransaction(tx3b_hex, True)
@@ -525,7 +525,7 @@ class ReplaceByFeeTest(BitcoinTestFramework):
         # correctly used by replacement logic
 
         # 1. Check that feeperkb uses modified fees
-        tx0_outpoint = make_utxo(self.nodes[0], 1.1*COIN)
+        tx0_outpoint = make_utxo(self.nodes[0], int(1.1*COIN))
 
         tx1a = CTransaction()
         tx1a.vin = [CTxIn(tx0_outpoint, nSequence=0)]
@@ -536,7 +536,7 @@ class ReplaceByFeeTest(BitcoinTestFramework):
         # Higher fee, but the actual fee per KB is much lower.
         tx1b = CTransaction()
         tx1b.vin = [CTxIn(tx0_outpoint, nSequence=0)]
-        tx1b.vout = [CTxOut(0.001*COIN, CScript([b'a'*740000]))]
+        tx1b.vout = [CTxOut(int(0.001*COIN), CScript([b'a'*740000]))]
         tx1b_hex = txToHex(tx1b)
 
         # Verify tx1b cannot replace tx1a.
@@ -556,7 +556,7 @@ class ReplaceByFeeTest(BitcoinTestFramework):
         assert(tx1b_txid in self.nodes[0].getrawmempool())
 
         # 2. Check that absolute fee checks use modified fee.
-        tx1_outpoint = make_utxo(self.nodes[0], 1.1*COIN)
+        tx1_outpoint = make_utxo(self.nodes[0], int(1.1*COIN))
 
         tx2a = CTransaction()
         tx2a.vin = [CTxIn(tx1_outpoint, nSequence=0)]
@@ -567,7 +567,7 @@ class ReplaceByFeeTest(BitcoinTestFramework):
         # Lower fee, but we'll prioritise it
         tx2b = CTransaction()
         tx2b.vin = [CTxIn(tx1_outpoint, nSequence=0)]
-        tx2b.vout = [CTxOut(1.01*COIN, CScript([b'a']))]
+        tx2b.vout = [CTxOut(int(1.01*COIN), CScript([b'a']))]
         tx2b.rehash()
         tx2b_hex = txToHex(tx2b)
 
diff --git a/qa/rpc-tests/rest.py b/qa/rpc-tests/rest.py
index 8c8353650..3c8a405bd 100755
--- a/qa/rpc-tests/rest.py
+++ b/qa/rpc-tests/rest.py
@@ -11,8 +11,9 @@
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import *
 from struct import *
+from io import BytesIO
+from codecs import encode
 import binascii
-import StringIO
 
 try:
     import http.client as httplib
@@ -146,7 +147,7 @@ class RESTTest (BitcoinTestFramework):
         binaryRequest += pack("i", 0)
 
         bin_response = http_post_call(url.hostname, url.port, '/rest/getutxos'+self.FORMAT_SEPARATOR+'bin', binaryRequest)
-        output = StringIO.StringIO()
+        output = BytesIO()
         output.write(bin_response)
         output.seek(0)
         chainHeight = unpack("i", output.read(4))[0]
@@ -233,7 +234,7 @@ class RESTTest (BitcoinTestFramework):
         assert_equal(response_hex.status, 200)
         assert_greater_than(int(response_hex.getheader('content-length')), 160)
         response_hex_str = response_hex.read()
-        assert_equal(response_str.encode("hex")[0:160], response_hex_str[0:160])
+        assert_equal(encode(response_str, "hex")[0:160], response_hex_str[0:160])
 
         # compare with hex block header
         response_header_hex = http_get_call(url.hostname, url.port, '/rest/headers/1/'+bb_hash+self.FORMAT_SEPARATOR+"hex", True)
@@ -241,7 +242,7 @@ class RESTTest (BitcoinTestFramework):
         assert_greater_than(int(response_header_hex.getheader('content-length')), 160)
         response_header_hex_str = response_header_hex.read()
         assert_equal(response_hex_str[0:160], response_header_hex_str[0:160])
-        assert_equal(response_header_str.encode("hex")[0:160], response_header_hex_str[0:160])
+        assert_equal(encode(response_header_str, "hex")[0:160], response_header_hex_str[0:160])
 
         # check json format
         block_json_string = http_get_call(url.hostname, url.port, '/rest/block/'+bb_hash+self.FORMAT_SEPARATOR+'json')
diff --git a/qa/rpc-tests/smartfees.py b/qa/rpc-tests/smartfees.py
index b209ae0c1..2c064ad8a 100755
--- a/qa/rpc-tests/smartfees.py
+++ b/qa/rpc-tests/smartfees.py
@@ -105,7 +105,7 @@ def check_estimates(node, fees_seen, max_invalid, print_estimates = True):
         print([str(all_estimates[e-1]) for e in [1,2,3,6,15,25]])
     delta = 1.0e-6 # account for rounding error
     last_e = max(fees_seen)
-    for e in filter(lambda x: x >= 0, all_estimates):
+    for e in [x for x in all_estimates if x >= 0]:
         # Estimates should be within the bounds of what transactions fees actually were:
         if float(e)+delta < min(fees_seen) or float(e)-delta > max(fees_seen):
             raise AssertionError("Estimated fee (%f) out of range (%f,%f)"
@@ -219,7 +219,7 @@ class EstimateFeeTest(BitcoinTestFramework):
                 from_index = random.randint(1,2)
                 (txhex, fee) = small_txpuzzle_randfee(self.nodes[from_index], self.confutxo,
                                                       self.memutxo, Decimal("0.005"), min_fee, min_fee)
-                tx_kbytes = (len(txhex)/2)/1000.0
+                tx_kbytes = (len(txhex) // 2) / 1000.0
                 self.fees_per_kb.append(float(fee)/tx_kbytes)
             sync_mempools(self.nodes[0:3],.1)
             mined = mining_node.getblock(mining_node.generate(1)[0],True)["tx"]
diff --git a/qa/rpc-tests/test_framework/blockstore.py b/qa/rpc-tests/test_framework/blockstore.py
index b9775b477..73d9ffbb2 100644
--- a/qa/rpc-tests/test_framework/blockstore.py
+++ b/qa/rpc-tests/test_framework/blockstore.py
@@ -3,8 +3,9 @@
 #             and for constructing a getheaders message
 #
 
-from mininode import *
+from .mininode import *
 import dbm
+from io import BytesIO
 
 class BlockStore(object):
     def __init__(self, datadir):
@@ -21,7 +22,7 @@ class BlockStore(object):
             serialized_block = self.blockDB[repr(blockhash)]
         except KeyError:
             return None
-        f = cStringIO.StringIO(serialized_block)
+        f = BytesIO(serialized_block)
         ret = CBlock()
         ret.deserialize(f)
         ret.calc_sha256()
@@ -115,7 +116,7 @@ class TxStore(object):
             serialized_tx = self.txDB[repr(txhash)]
         except KeyError:
             return None
-        f = cStringIO.StringIO(serialized_tx)
+        f = BytesIO(serialized_tx)
         ret = CTransaction()
         ret.deserialize(f)
         ret.calc_sha256()
diff --git a/qa/rpc-tests/test_framework/blocktools.py b/qa/rpc-tests/test_framework/blocktools.py
index b075f69c4..afa0f5f9b 100644
--- a/qa/rpc-tests/test_framework/blocktools.py
+++ b/qa/rpc-tests/test_framework/blocktools.py
@@ -4,8 +4,8 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 #
 
-from mininode import *
-from script import CScript, OP_TRUE, OP_CHECKSIG
+from .mininode import *
+from .script import CScript, OP_TRUE, OP_CHECKSIG
 
 # Create a block (with regtest difficulty)
 def create_block(hashprev, coinbase, nTime=None):
@@ -29,7 +29,7 @@ def serialize_script_num(value):
     neg = value < 0
     absvalue = -value if neg else value
     while (absvalue):
-        r.append(chr(absvalue & 0xff))
+        r.append(int(absvalue & 0xff))
         absvalue >>= 8
     if r[-1] & 0x80:
         r.append(0x80 if neg else 0)
diff --git a/qa/rpc-tests/test_framework/comptool.py b/qa/rpc-tests/test_framework/comptool.py
index f19edbf06..6279070fb 100755
--- a/qa/rpc-tests/test_framework/comptool.py
+++ b/qa/rpc-tests/test_framework/comptool.py
@@ -4,9 +4,9 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 #
 
-from mininode import *
-from blockstore import BlockStore, TxStore
-from util import p2p_port
+from .mininode import *
+from .blockstore import BlockStore, TxStore
+from .util import p2p_port
 
 '''
 This is a tool for comparing two or more bitcoinds to each other
diff --git a/qa/rpc-tests/test_framework/mininode.py b/qa/rpc-tests/test_framework/mininode.py
index 20386c642..53f5e8805 100755
--- a/qa/rpc-tests/test_framework/mininode.py
+++ b/qa/rpc-tests/test_framework/mininode.py
@@ -24,7 +24,8 @@ import binascii
 import time
 import sys
 import random
-import cStringIO
+from io import BytesIO
+from codecs import encode
 import hashlib
 from threading import RLock
 from threading import Thread
@@ -75,12 +76,12 @@ def deser_string(f):
 
 def ser_string(s):
     if len(s) < 253:
-        return chr(len(s)) + s
+        return struct.pack("B", len(s)) + s
     elif len(s) < 0x10000:
-        return chr(253) + struct.pack("<H", len(s)) + s
+        return struct.pack("<BH", 253, len(s)) + s
     elif len(s) < 0x100000000L:
-        return chr(254) + struct.pack("<I", len(s)) + s
-    return chr(255) + struct.pack("<Q", len(s)) + s
+        return struct.pack("<BI", 254, len(s)) + s
+    return struct.pack("<BQ", 255, len(s)) + s
 
 
 def deser_uint256(f):
@@ -132,13 +133,13 @@ def deser_vector(f, c):
 def ser_vector(l):
     r = ""
     if len(l) < 253:
-        r = chr(len(l))
+        r = struct.pack("B", len(l))
     elif len(l) < 0x10000:
-        r = chr(253) + struct.pack("<H", len(l))
+        r = struct.pack("<BH", 253, len(l))
     elif len(l) < 0x100000000L:
-        r = chr(254) + struct.pack("<I", len(l))
+        r = struct.pack("<BI", 254, len(l))
     else:
-        r = chr(255) + struct.pack("<Q", len(l))
+        r = struct.pack("<BQ", 255, len(l))
     for i in l:
         r += i.serialize()
     return r
@@ -162,13 +163,13 @@ def deser_uint256_vector(f):
 def ser_uint256_vector(l):
     r = ""
     if len(l) < 253:
-        r = chr(len(l))
+        r = struct.pack("B", len(l))
     elif len(l) < 0x10000:
-        r = chr(253) + struct.pack("<H", len(l))
+        r = struct.pack("<BH", 253, len(l))
     elif len(l) < 0x100000000L:
-        r = chr(254) + struct.pack("<I", len(l))
+        r = struct.pack("<BI", 254, len(l))
     else:
-        r = chr(255) + struct.pack("<Q", len(l))
+        r = struct.pack("<BQ", 255, len(l))
     for i in l:
         r += ser_uint256(i)
     return r
@@ -192,13 +193,13 @@ def deser_string_vector(f):
 def ser_string_vector(l):
     r = ""
     if len(l) < 253:
-        r = chr(len(l))
+        r = struct.pack("B", len(l))
     elif len(l) < 0x10000:
-        r = chr(253) + struct.pack("<H", len(l))
+        r = struct.pack("<BH", 253, len(l))
     elif len(l) < 0x100000000L:
-        r = chr(254) + struct.pack("<I", len(l))
+        r = struct.pack("<BI", 254, len(l))
     else:
-        r = chr(255) + struct.pack("<Q", len(l))
+        r = struct.pack("<BQ", 255, len(l))
     for sv in l:
         r += ser_string(sv)
     return r
@@ -222,20 +223,20 @@ def deser_int_vector(f):
 def ser_int_vector(l):
     r = ""
     if len(l) < 253:
-        r = chr(len(l))
+        r = struct.pack("B", len(l))
     elif len(l) < 0x10000:
-        r = chr(253) + struct.pack("<H", len(l))
+        r = struct.pack("<BH", 253, len(l))
     elif len(l) < 0x100000000L:
-        r = chr(254) + struct.pack("<I", len(l))
+        r = struct.pack("<BI", 254, len(l))
     else:
-        r = chr(255) + struct.pack("<Q", len(l))
+        r = struct.pack("<BQ", 255, len(l))
     for i in l:
         r += struct.pack("<i", i)
     return r
 
 # Deserialize from a hex string representation (eg from RPC)
 def FromHex(obj, hex_string):
-    obj.deserialize(cStringIO.StringIO(binascii.unhexlify(hex_string)))
+    obj.deserialize(BytesIO(binascii.unhexlify(hex_string)))
     return obj
 
 # Convert a binary-serializable object to hex (eg for submission via RPC)
@@ -423,7 +424,7 @@ class CTransaction(object):
     def calc_sha256(self):
         if self.sha256 is None:
             self.sha256 = uint256_from_str(hash256(self.serialize()))
-        self.hash = hash256(self.serialize())[::-1].encode('hex_codec')
+        self.hash = encode(hash256(self.serialize())[::-1], 'hex')
 
     def is_valid(self):
         self.calc_sha256()
@@ -492,7 +493,7 @@ class CBlockHeader(object):
             r += struct.pack("<I", self.nBits)
             r += struct.pack("<I", self.nNonce)
             self.sha256 = uint256_from_str(hash256(r))
-            self.hash = hash256(r)[::-1].encode('hex_codec')
+            self.hash = encode(hash256(r)[::-1], 'hex')
 
     def rehash(self):
         self.sha256 = None
@@ -640,7 +641,7 @@ class msg_version(object):
     def __init__(self):
         self.nVersion = MY_VERSION
         self.nServices = 1
-        self.nTime = time.time()
+        self.nTime = int(time.time())
         self.addrTo = CAddress()
         self.addrFrom = CAddress()
         self.nNonce = random.getrandbits(64)
@@ -985,7 +986,7 @@ class msg_reject(object):
 
     def __init__(self):
         self.message = ""
-        self.code = ""
+        self.code = 0
         self.reason = ""
         self.data = 0L
 
@@ -1251,43 +1252,46 @@ class NodeConn(asyncore.dispatcher):
             self.sendbuf = self.sendbuf[sent:]
 
     def got_data(self):
-        while True:
-            if len(self.recvbuf) < 4:
-                return
-            if self.recvbuf[:4] != self.MAGIC_BYTES[self.network]:
-                raise ValueError("got garbage %s" % repr(self.recvbuf))
-            if self.ver_recv < 209:
-                if len(self.recvbuf) < 4 + 12 + 4:
+        try:
+            while True:
+                if len(self.recvbuf) < 4:
                     return
-                command = self.recvbuf[4:4+12].split("\x00", 1)[0]
-                msglen = struct.unpack("<i", self.recvbuf[4+12:4+12+4])[0]
-                checksum = None
-                if len(self.recvbuf) < 4 + 12 + 4 + msglen:
-                    return
-                msg = self.recvbuf[4+12+4:4+12+4+msglen]
-                self.recvbuf = self.recvbuf[4+12+4+msglen:]
-            else:
-                if len(self.recvbuf) < 4 + 12 + 4 + 4:
-                    return
-                command = self.recvbuf[4:4+12].split("\x00", 1)[0]
-                msglen = struct.unpack("<i", self.recvbuf[4+12:4+12+4])[0]
-                checksum = self.recvbuf[4+12+4:4+12+4+4]
-                if len(self.recvbuf) < 4 + 12 + 4 + 4 + msglen:
-                    return
-                msg = self.recvbuf[4+12+4+4:4+12+4+4+msglen]
-                th = sha256(msg)
-                h = sha256(th)
-                if checksum != h[:4]:
-                    raise ValueError("got bad checksum " + repr(self.recvbuf))
-                self.recvbuf = self.recvbuf[4+12+4+4+msglen:]
-            if command in self.messagemap:
-                f = cStringIO.StringIO(msg)
-                t = self.messagemap[command]()
-                t.deserialize(f)
-                self.got_message(t)
-            else:
-                self.show_debug_msg("Unknown command: '" + command + "' " +
-                                    repr(msg))
+                if self.recvbuf[:4] != self.MAGIC_BYTES[self.network]:
+                    raise ValueError("got garbage %s" % repr(self.recvbuf))
+                if self.ver_recv < 209:
+                    if len(self.recvbuf) < 4 + 12 + 4:
+                        return
+                    command = self.recvbuf[4:4+12].split("\x00", 1)[0]
+                    msglen = struct.unpack("<i", self.recvbuf[4+12:4+12+4])[0]
+                    checksum = None
+                    if len(self.recvbuf) < 4 + 12 + 4 + msglen:
+                        return
+                    msg = self.recvbuf[4+12+4:4+12+4+msglen]
+                    self.recvbuf = self.recvbuf[4+12+4+msglen:]
+                else:
+                    if len(self.recvbuf) < 4 + 12 + 4 + 4:
+                        return
+                    command = self.recvbuf[4:4+12].split("\x00", 1)[0]
+                    msglen = struct.unpack("<i", self.recvbuf[4+12:4+12+4])[0]
+                    checksum = self.recvbuf[4+12+4:4+12+4+4]
+                    if len(self.recvbuf) < 4 + 12 + 4 + 4 + msglen:
+                        return
+                    msg = self.recvbuf[4+12+4+4:4+12+4+4+msglen]
+                    th = sha256(msg)
+                    h = sha256(th)
+                    if checksum != h[:4]:
+                        raise ValueError("got bad checksum " + repr(self.recvbuf))
+                    self.recvbuf = self.recvbuf[4+12+4+4+msglen:]
+                if command in self.messagemap:
+                    f = BytesIO(msg)
+                    t = self.messagemap[command]()
+                    t.deserialize(f)
+                    self.got_message(t)
+                else:
+                    self.show_debug_msg("Unknown command: '" + command + "' " +
+                                        repr(msg))
+        except Exception as e:
+            print 'got_data:', repr(e)
 
     def send_message(self, message, pushbuf=False):
         if self.state != "connected" and not pushbuf:
diff --git a/qa/rpc-tests/test_framework/netutil.py b/qa/rpc-tests/test_framework/netutil.py
index bfdef76ad..bbc58a14e 100644
--- a/qa/rpc-tests/test_framework/netutil.py
+++ b/qa/rpc-tests/test_framework/netutil.py
@@ -45,7 +45,7 @@ def _convert_ip_port(array):
     # convert host from mangled-per-four-bytes form as used by kernel
     host = binascii.unhexlify(host)
     host_out = ''
-    for x in range(0, len(host)/4):
+    for x in range(0, len(host) // 4):
         (val,) = struct.unpack('=I', host[x*4:(x+1)*4])
         host_out += '%08x' % val
 
diff --git a/qa/rpc-tests/test_framework/socks5.py b/qa/rpc-tests/test_framework/socks5.py
index 1dbfb98d5..12327a6c5 100644
--- a/qa/rpc-tests/test_framework/socks5.py
+++ b/qa/rpc-tests/test_framework/socks5.py
@@ -117,7 +117,7 @@ class Socks5Connection(object):
             self.serv.queue.put(cmdin)
             print('Proxy: ', cmdin)
             # Fall through to disconnect
-        except Exception,e:
+        except Exception as e:
             traceback.print_exc(file=sys.stderr)
             self.serv.queue.put(e)
         finally:
diff --git a/qa/rpc-tests/test_framework/test_framework.py b/qa/rpc-tests/test_framework/test_framework.py
index 584f318d0..19ee47260 100755
--- a/qa/rpc-tests/test_framework/test_framework.py
+++ b/qa/rpc-tests/test_framework/test_framework.py
@@ -26,7 +26,7 @@ from .util import (
     check_json_precision,
     initialize_chain_clean,
 )
-from authproxy import AuthServiceProxy, JSONRPCException
+from .authproxy import AuthServiceProxy, JSONRPCException
 
 
 class BitcoinTestFramework(object):
@@ -140,7 +140,7 @@ class BitcoinTestFramework(object):
             print("JSONRPC error: "+e.error['message'])
             traceback.print_tb(sys.exc_info()[2])
         except AssertionError as e:
-            print("Assertion failed: "+e.message)
+            print("Assertion failed: "+ str(e))
             traceback.print_tb(sys.exc_info()[2])
         except Exception as e:
             print("Unexpected exception caught during testing: "+str(e))
diff --git a/qa/rpc-tests/wallet.py b/qa/rpc-tests/wallet.py
index e6ce39711..cb876aae5 100755
--- a/qa/rpc-tests/wallet.py
+++ b/qa/rpc-tests/wallet.py
@@ -249,7 +249,7 @@ class WalletTest (BitcoinTestFramework):
         errorString = ""
         try:
             txId  = self.nodes[0].sendtoaddress(self.nodes[2].getnewaddress(), "1f-4")
-        except JSONRPCException,e:
+        except JSONRPCException as e:
             errorString = e.error['message']
 
         assert("Invalid amount" in errorString)
@@ -257,7 +257,7 @@ class WalletTest (BitcoinTestFramework):
         errorString = ""
         try:
             self.nodes[0].generate("2") #use a string to as block amount parameter must fail because it's not interpreted as amount
-        except JSONRPCException,e:
+        except JSONRPCException as e:
             errorString = e.error['message']
 
         assert("not an integer" in errorString)
@@ -271,7 +271,7 @@ class WalletTest (BitcoinTestFramework):
         # Check that the txid and balance is found by node1
         try:
             self.nodes[1].gettransaction(cbTxId)
-        except JSONRPCException,e:
+        except JSONRPCException as e:
             assert("Invalid or non-wallet transaction id" not in e.error['message'])
 
         #check if wallet or blochchain maintenance changes the balance