What to do if there's a Mews Connector app error notification?

If the action works, but Mews still notifies an error, then you have duplicate Mews Connector apps.

 

When you have more than one instance of the Mews Connector app, both versions process the command, but the receiving device (printer, key cutter, etc.) can only process once at a time.

 

To resolve this, follow the steps in this article Duplicate Mews Connector apps