Flag could not be deleted

What causes this issue?

The flag for the personnel number you a currently processing could not
be deleted from table T77INT.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Please check your system settings for extended integration
(table T77S0, switch PLOGI EVENB), and check if table T77INT has
flagged entries.

Error message extract from SAP system. Copyright SAP SE.