Model &1/&2/&3 is currently being activated/deactivated by user &4

What causes this issue?

At least one parallel activation or deactivation of this integration
mode is currently taking place.
Integration model &V1& / &V2& / &V3& is already being processed by user
&V4&.

System Response

Parallel activation or deactivation of an integration model (including
different versions) using different activation runs is not allowed. As
a result, the activation run is terminated.

How to fix this error?

Coordinate your activities with other users.

Error message extract from SAP system. Copyright SAP SE.