Comparing two .txt files using difflib in Python
For starters, you need to pass strings to difflib.SequenceMatcher, not files: # Like so difflib.SequenceMatcher(None, str1, str2) # Or just read the files in difflib.SequenceMatcher(None, file1.read(), file2.read()) That’ll fix your error. To get the first non-matching string, see the difflib documentation.