Check table &1 is not compatible

What causes this issue?

You have tried to use a check table for an extension that is not
compatible.
A compatible check table has to fullfil the following requirements:
It must not have more than one key field, except the client field
The data type of the key field must be based on a domain
A check table can have a related text table. The first character-type
field will be shown as a description in a value help.

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?

Use another check table or change the table definition accordingly.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.