See my answer.
In real-world data this is a real problem: multiple, mismatched, incomplete, inconsistent and multilanguage/region date formats, often mixed freely in one dataset. It's not ok for production code to fail, let alone go exception-happy like a fox.
We need to try...catch multiple datetime formats fmt1,fmt2,...,fmtn and suppress/handle the exceptions (from strptime()) for all those that mismatch (and in particular, avoid needing a yukky n-deep indented ladder of try..catch clauses). From my solution
def try_strptime(s, fmts=['%d-%b-%y','%m/%d/%Y']): for fmt in fmts: try: return datetime.strptime(s, fmt) except: continue return None # or reraise the ValueError if no format matched, if you prefer