Opera browser gives 403 FORBIDDEN when trying to access my SharePoint site. The site uses FBA authentication and is an internet facing site. In IIS logs I can see that Opera has requested the favicon. The site works fine with other major browsers (I7, I8, I9, FF, Chrome, Safari). The same problem occurs with http and https.
Please find a similar issue reported in msdn with FBA authentication and Opera browser.
As the post suggests,
Opera browser is not on the supported browser list for SharePoint. Chrome isn't on the list either, although that one normally works. Opera has always had issues with SharePoint and it isn't fixed in 2010. Here's the list of approved browsers.