This might happen if:

- Web Connector doesn’t have permission to open or make changes to the file.

- The file doesn’t exist.

- Your hard drive is full.

What you can do? 

Sign in to your computer as a Windows admin and set up QuickBooks Web Connector.

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