Company code &2 already used for dig. signature and must not be changed

What causes this issue?

You have changed the company code that is specified for a number range
number. However, digital signatures have already been created for
documents that use this number range number and the company code must
therefore not be changed.

System Response

How to fix this error?

Reverse the change.

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.