If you use Zotero and have a Zotero Connector installed in your browser, Zotero may have associated Google Scholar with its automatic proxy functionality. However, Harvard's proxy server and Google Scholar interfere with each other's functionality, unfortunately. As a result, you may be see the following error message when accessing Google Scholar:
There are two ways to fix this:
Reload Google Scholar. You should see a yellow bar at the top of the page. In that yellow bar, click on "Don't proxy this site."
Select the tab labeled "Proxies," then select the Harvard proxy in the middle of the page. This will make a list of sites appear that are automatically routed through the proxy server. In that list, find scholar.google.com (you should be able to do that using the find function in your browser), and select it. Then remove Google Scholar from the list by clicking on the button with the minus sign.
Once you have removed Google Scholar from the automatic proxy configuration, make sure to set up your affiliation with Harvard University, which will enable you to check if you have access to articles cited in Google Scholar (you should see a link to "try Harvard Library" next to citations when this is properly set up).