Interface &1 cannot be reset (modification without MA)

What causes this issue?

The interface has been modified without the modification assistant. The
original is no longer available. Therefore the 'Reset to original'
function cannot be executed for this object.

System Response

You can attempt to call up an original version of the object using
version management. The object will, however, still be classified as
modified. You can reset this setting during the next upgrade.

How to fix this error?

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

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.