I had the same problem, and my problem was resolved after upgrading to version 5.19.
- dzyang
Before posting, please read how to report bug or request support effectively.
Bug reports without an attached log file are usually useless.
Authentication log (see session log for details):
Unable to load key file "C:\Users\navid\OneDrive\Desktop\Keys\private.ppk" (PuTTY key format too new)
Using username "ubuntu".
Authentication failed.