This has been reported to us recently. You can safely ignore this error as you should have another method of backing up the server anyways. It doesn’t affect the inner workings of WAM.
This was a feature stream we added for doing backups before the software runs certain routines. During our testing, it didn’t give any errors. We’ve found out that it doesn’t do it in every case, but if the SQLPS module is not loaded, and auto-loading of modules is not enabled, then this error occurs.
This will be switched to an optional feature stream in the future, disabled by default, and will have checks to make sure the SQLPS module is loaded so that these errors don’t occur anymore.