Computed Attribute &1 corrupt. Customizing part not saved !!!

What causes this issue?

For Computed Attribute &v1& the customizing part was not saved. The
CGPL_PROJECT EXTERNAL_ID is &v2&

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?

Create an internal CSN with the exact UI steps that were taken and exact
application data that was used.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.