ORA-01017: invalid username/password;logon denied
I have seen this only once so far, but there is an issue described in the My Oracle Suppport note:

FIPS use causes ORA-01017: Invalid Username/password with Managed ODP.NET (Doc ID 1937500.1)

I will not post the full content of this as it is not public, but here is the essence:


  This bug has been fixed in 12.1.0.2 Managed Provider. Please note that the DB version must be 12.1.0.2 or higher for this fix to work as expected. 
  
  The workaround is to set in the registry
  System\CurrentControlSet\Control\Lsa\FIPSAlgorithmPolicy\Enabled to
  0.


Some public references to this matter:

https://stackoverflow.com/questions/26410951/oracle-manageddataaccess-and-ora-01017-invalid-username-password-logon-denied

https://stackoverflow.com/questions/31785650/ora-01005-error-connecting-with-odp-net

https://community.oracle.com/thread/2557592?start=0&amp;tstart=0