Current version of data in database has changed since user initiated update process. Error occurred in Oracle Apex

Current version of data in database has changed since user initiated update process. 

Error occurred in Oracle Apex

This error can occur for many reasons, but one of the most common reasons is when the same row is updated by multiple parties at the same time. In my case, I get the error when updating a flag in my table. 

Then I realized that when I update the flag a trigger also fires and the same row inside the trigger gets updated again. So I faced a problem.