This happens when your application didn’t install correctly on your computer.

What you can do?

1. Close any open windows in Web Connector.

2. Exit and reopen Web Connector.

Note: If you don’t see your application in Web Connector after you restart, add the .QWC file for your third-party application. You can get the .QWC file from your application provider, and it must be downloaded to your computer.

Reference: https://quickbooks.intuit.com/learn-support/en-us/set-up-payments/fix-common-web-connector-errors/00/203305