ORA-01017: invalid username/password; logon denied I've come across the abnormal situation, and can't understand what happens.

I am connecting databases using PL/SQL Developer 8.0.4.1514(I've also tried v7,but same) . Sometimes(When I am trying to log on, or when I open another session, or when I am trying to run query in previously opened session) this error message appears



Sometimes after 3 tries error resolves(using the same password on each try), sometimes it needs one try to resolve...

What may be the reason?

Thank you ...
PL/SQL Developer will remember your most recent windows. If you close the application without closing your windows, it will attempt to authenticate to restart your old sessions. This can become a nuisance if you work in several environments. Try making it habit to close everything before closing the application. You may also try upgrading the application as user21081 suggested.