Utilizations for limit type &1 are being processed by another STC

What causes this issue?

Default Risk and Limit System:
The utilizations for a limit in limit type &V1&, to which the
transaction is to be attributed, are being processed in a parallel
single transaction check.

System Response

The utilization of this transaction cannot be updated.

How to fix this error?

Restart the single transaction check.

Error message extract from SAP system. Copyright SAP SE.