If you had used Zotero to redirect links through the proxy server, it will redirect you to the old login method. You will see a message like this at the top of your screen:

To disable Zotero's proxy redirect, you can click on "Proxy settings" in the message above. Or go to the Chrome plugins, click the 3 dots next to Zotero Connector, and select "options:"

Choose "Proxies" on the left, and then uncheck the box for "Enable proxy redirection:"