The sections of class & have been reset to its original version

What causes this issue?

All modifications within the public, protected and private section of
the class have been discarded. Nevertheless, the method implementations
can still contain modifications.

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?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.