import sys
reload(sys)
sys.setdefaultencoding('utf8')
Its just a guess as there is no code but if your code used to work in python3 and not in Python2 then this was the only problem I could think of. Try this if it helps. Otherwise its very difficult to recognize the issue.
NOTE: I may help you in private too but by looking at the question title bytes error, this code usually will solve the issue, just place it at the top after your imports.
6
solved Fix “UnicodeDecodeError: can’t decode byte