Foxmarks: Error: Forbidden

From Foxmarks Wiki

Foxmarks Version 2.0.1 and above

If you see this error message, it typically means that you have disabled cookies. In order for Foxmarks Bookmark Synchronizer v2 and above to work, you must have enabled cookies for the domains sync.foxmarks.com and login.foxmarks.com. If it still doesn't work, enable cookies for the domain foxmarks.com (leave out sync.). If that still doesn't work, try enabling full encryption by going to Tools > Foxmarks > Settings > Advanced tab > Encryption > "Encrypt All".

If you have upgraded one of your computers to Foxmarks Bookmark Synchronizer 2.0, you may see this message if you attempt to use an earlier version of the Foxmarks Bookmark Synchronizer (e.g., 1.0.1 or earlier). Once you have upgraded one computer to Foxmarks version 2.0, you must upgrade all of your computers.

Finally, some users have seen this error due to a firewall or proxy (such as ZoneAlarm) blocking requests sent to sync.foxmarks.com--check your foxmarks.log file to see if that's the case.