Web Page Blocked The page you have requested has been blocked because the URL is banned.
Local URLfilter Block
It looks like you're on a network that's intercepting and blocking some traffic.
Zotero should show a clearer error, I guess, but since it's supposed to be connecting securely to Zotero servers and something is intercepting the connection and returning a 403 Forbidden error, this just isn't an expected situation.
Zotero should show a clearer error, I guess, but since it's supposed to be connecting securely to Zotero servers and something is intercepting the connection and returning a 403 Forbidden error, this just isn't an expected situation.