Action merging: Only & processed action(s) allowed for each partner

What causes this issue?

In the technology used for the action merging, only the predefined
number of processed actions for each document partner is allowed.

System Response

All further actions for this document partner that are found are
deleted.

How to fix this error?

You make the setting for the action merging in the Customizing of the
action definition.

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.