QBWC1016: No application was selected for update

This happens when you selected Update in Web Connector without first selecting any applications to update.

What you can do?

Select the application you want to update, then select Update Selected.

Note: If you still get this error, reach out to Intuit Support.

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