How To Fix WES_OUTBOUND015 - Error during proxy call (&1: &2, &3)

SAP Error Message - Details

• Message type: E = Error

• Message class: WES_OUTBOUND - Messages for Outbound Services

• Message number: 015

• Message text: Error during proxy call (&1: &2, &3)

What causes this issue?

An error occurred during the proxy call for the service.
The error text is:
Longtext:

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

System Response

How to fix this error?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.