Blank Page Issue faced when Upgradation

We have Upgraded the Database and Application after upgradation we are facing this issue in Workflow

Database Upgradation from 10g to  12c Database

Application Upgradation from 12.0.X to  12.2.X

Issue : Final Approver approvers a transaction request where that workflow has reference to DB link then the Issue is reproducible. After approval when user clicks on any notification the page appears to be blank as in the below screenshot. This gets resolved after certain period of time(approx. 15 minutes) or when Bouncing the server.

Root Cause : We have analyzed and tested that this Issue is due to the DB link which is being called in Workflow package at approval.

Note : If the DB link as_persons is called in any workflow the same Issue gets replicated.

Solution/Fix : To Upgrade the database that is causing the Issue.

Feel free to give any suggestions