Extended integration is not active

What causes this issue?

Extended integration is not active. However, an entry already exists in
table T77INT for the current personnel number.
This entry will not be deleted.

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?

Decide if you want to use extended integration (switch PLOGI EVENB in
table T77S0), and check which entries are flagged in your system (table
T77INT).

Error message extract from SAP system. Copyright SAP SE.