Fixed value definition is not allowed for data type &

What causes this issue?

Fixed value maintenance is not possible for the specified data type.
Values for data types CHAR, NUMC, DEC, INT1, INT2 and INT4 can be
specified for a domain. However, only in the case of data types CHAR and
NUMC is a check of the entry values on the mask carried out.

System Response

This is information.

How to fix this error?

If fixed values are defined for the domain, correct the data type or
delete the fixed values.

Error message extract from SAP system. Copyright SAP SE.