Q: Extension ID is empty! Try later, how to fix this?
A: Please make sure that your file exchange sync chrome extension(s) are set up and configured properly and that you are logged into eBay/eBay file exchange, depending on which you're using (please note that part of the issue may have been that you switched between using file exchange chrome extension lister and another eBay listing option, for example, the eBay selling manager). Then go to your List & Export Settings and click Save Settings. That should stop that issue.