No test possible since directory '&' does not exist or cannot be read

What causes this issue?

The existence and the type of the command file should be tested.
However, the directory entered is not available or cannot be accessed
from the application server.

System Response

No test is performed.

How to fix this error?

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

Procedure for System Administrators

You must check the availabilty and that the command file entered works
outside the SAP system with operating systems.

Error message extract from SAP system. Copyright SAP SE.