Specify a client-specific application table

What causes this issue?

The table is defined with delivery class A (application table - master
data and movement data) but does not have a client field in its key.
In today's common OLTP SAP Systems this is not sufficient to separate
data on a client-specific basis. In multi-client applications, this may
therefore result in unintentional data losses or the accidental display
of data pertaining to another client.

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?

If the delivery class is correct, check if it is okay that the table key
does not contain a client field. If no, add the client field.
If the table should be cross-client and the wrong delivery class was
assigned, use the correct delivery class.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.