The output length for the material number is too small

What causes this issue?

The combination of manufacturer part number and external manufacturer
is larger than the current output length for the material number. If
the output length of the material number is again set to a value that
is not long enough to use the manufacturer part number and external
manufacturer, the material number can no longer be input.

System Response

In all material fields, the internal material number will be output or
will have to be input.

How to fix this error?

Change your material master records so that the manufacturer part
number is unique or abbreviate the manufacturer part number.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.