Failed to generate request: (Mandatory XML element missing)

This error indicates that the files which the underlying license service reference are not accessible or corrupted.

First, ensure that the running user has the user permissions required to run TOP Server so that the files are accessible.

If the user does have the correct permissions but you are still seeing this error, the files are likely corrupted.

This can occur if a machine is cloned, restored from a backup/image, or otherwise modified. For more details, please see What Can Cause a Broken TOP Server License?

In this case, you will need to clear your TOP Server Trusted Storage. See: How to clear TOP Server Trusted Storage