SAP Message C0557 - Message category & is not defined

Diagnosis
The current message or the message to be used to report the selectedvalue or text belongs to message category &V1&.However, this message category is not defined in Customizing (anymore).

Procedure
RESET N1
Check the definitions of the message categories in Customizing andcorrect them if necessary.
If the error has occurred in the PI sheet, call up the PI sheet again.
Repeat the desired function.