System error (text name empty in text object & and text ID &)

What causes this issue?

A system error has occurred. The document number could not be assigned
to the individual texts of the document.
It is therefore not possible to save the document.

How can this happen?

The newly created purchase order no. 45...100 contains text1 and text2.
The number 45...100 must be assigned to both texts. If this assignment
cannot be made, the system cannot find the texts for the document.

How to fix this error?

Please contact your system administrator.

Error message extract from SAP system. Copyright SAP SE.