Re: Audit Trial

Posted by ErmanArslansOracleBlog on Mar 24, 2017; 7:40am
URL: http://erman-arslan-s-oracle-forum.124.s1.nabble.com/Audit-Trial-tp2407p2415.html

This may be related with your problem.
Check this ->Forgot Password Function Shows GUEST As The Password Record Update Owner (Doc ID 1502551.1)

This is for EBS 12.1 and it is specially for fnd_user last_updated_by column, but it may indirectly fix your problem as well.
Check the last_updated_by column of fnd_user. If you see any GUEST or null there, then apply the patch documented in the above document.