If you installed the Zotero browser extension in 2022 or earlier (even if you uninstalled and reinstalled it recently), it can cause you to get proxy server errors like this one:
When you install the Zotero browser extension, it comes with proxy redirection enabled by default.
To resolve the problem, follow these four steps:
1. Find the extension in your browser settings. For Chrome browser, click on the kebab menu, select Extensions > Manage Extensions
2. Click on the Zotero Connector’s ‘Details’
3. Select ‘Extension options’
4. Go to the Proxies tab and deselect ‘Enable proxy redirection’
