Parameter &1 doesn't exist in the reading group &2.

What causes this issue?

The parameter does not exist in the reading group. The reading group was
changed.

System Response

Only displaying the parameter name and parameter description is
possible.

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.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.