Function module & could not be updated

What causes this issue?

A function module is generated for each matchcode object for
maintenance by the programs if at least one matchcode ID has update
type 'P'. This function module MC_UPDATE_<mconame> could not be
updated.

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?

This message implies an internal inconsistency. Check the definitions
of the relevant matchcode ID or of the relevant matchcode object in the
ABAP/4 Dictionary.

Error message extract from SAP system. Copyright SAP SE.