Flush error of control framework at &3, program &1, screen &2

What causes this issue?

A repairable error has occured during the data transfer between the
frontend (personal computer) and backend (applications server).

System Response

The current transaction is ended.

How to fix this error?

Start the transaction again.

Procedure for System Administrators

An exceptional condition has arisen during the synchronisation of the
automation queue (FLUSH in the control framework).

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.