Immediate processing was not possible

What causes this issue?

The IDoc is supposed to be immediately transferred to the application
for processing in a separate context.
An error has occurred, which is described more precisely below:
The module TH_ARFC_LOCAL_RESOURCES is called to check whether another
asynchronous process can be opened. This is not possible in the current
situation. The IDocs are therefore not transferred to the application.
The cause: &v1&&v2&.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Use report RBDAPP01 to transfer IDocs to the application.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.