With the Workflow system pre-R12, we assigned the owner of Workflow to be the SYSADMIN user and my boss entered his e-mail address in the FND_USER account for SYSADMIN so we could receive system e-mails and audit the account properly. This had an unintended side effect after we went live with 12.1.3, as he promptly received thousands of error notifications for the Workflow event oracle.apps.ar.applications.CashApp.apply which was odd since nothing was wrong in the system since it had passed all of the verification steps in order to release the system.
Looking further into this issue, it appears that the event subscriptions for this were turned on for the Oracle Projects module even though we didn't install it! You can reference MOS notes 973074.1 and 1313111.1 about how to turn off the subscription for PA_PWP_NOTIFICATION.Receive_BE and patch 8903995 if you really want to "fix" your system by installing the part of Oracle Projects that is looking for this subscription to be on.
Tonight I'm bringing you essentially part one of a series, as this was the start of a much larger issue for us. I thought after a long absence, this was a good place to start back up with the blog. :}