Error while modifying dynpro & (dynpro was not modified).

What causes this issue?

The flow logic of the screen &V1& is not that of a generated view
maintenance list screen. Either the screen has been considerably
modified manually, or the view which it is based on has no maintainable
key.

System Response

The screen has not been modified.

How to fix this error?

Make the view cluster maintenance screen modifications required
manually on the screen. See the transaction 'Generate table maintenance
dialog' application help for the modifications required.

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.

Error message extract from SAP system. Copyright SAP SE.