You cannot display a maintenance dialog for table/view &.

What causes this issue?

The 'Table maintenance' flag for the view/table &V1& in the ABAP
Dictionary is set to <ZH>not allowed</>, so there should be no dialog
for this table/view.
The 'Table maintenance' flag may have been changed to <ZH>not allowed
</> from <ZH>allowed</> or <ZH>allowed</> <ZH>with restrictions</>, so
there could still be a maintenance dialog.

System Response

The maintenance dialog is displayed, but it cannot be changed or
created again.

How to fix this error?

You should delete the existing maintenance dialog or check whether the
'Table maintenance' flag in the ABAP Dictionary can be set to
<ZH>allowed</> or <ZH>allowed</> <ZH>with restrictions</>.

Procedure for System Administrators

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.