Problem with SOAP class

What causes this issue?

The SOAP IDoc application could not be started successfully.

System Response

The problem occurred in the method call: &v1&
&v2&&v3&&v4&

How to fix this error?

Inform your system administrator.

Procedure for System Administrators

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

Error message extract from SAP system. Copyright SAP SE.