Error during deletion of assignment of group & & to doc. no. &

What causes this issue?

In the group definition for a multiple processing run, the selected
documents (transfer requirements or delivery notes) must refer to this
group. This assignment is set in a table (T311A). A system error
occurred during the attempt to delete this assignment.

How to fix this error?

INCLUDE SY_VE_HOLEN OBJECT DOKU ID TX LANGUAGE EN

Error message extract from SAP system. Copyright SAP SE.