In most cases, when you get Server error on retrieving products, it’s usually because the extension is either not installed correctly or the integration is not working. Here is a checklist of actions that can fix the problem:
1. Remove http authentication
if you’re trying to run Squarefeed from a dev site which has the front end password protected, the extension can’t communicate with our servers. Please remove password protection and try again
2. Check integration and tokens
In order for Squarefeed to work properly with your Magento store, it needs an active integration. This integration is created automatically when you install the extension.
To check, log into your Magento admin panel, the Go to System > Extensions > Integration and look for the integration called Squarefeed. It should appear in the list and it’s status should be Active.
If the integration exists and it is active, but you’re still getting the error, click on the Pencil icon next to it.
Under Integration Details you should see values populated for the following: Consumer Key, Consumer Secret, Access Token and Access Token Secret.

3. Check log
If there are any errors from our extension, it creates error logs on your server. magento_root/var/log/squarefeed.log should contain the info. In this case please contact our support support@squarefeed.io.
4. Reinstall
In case of any issues, please reinstall the extension via Composer as described here.