Author: Andrew Gregory
One long-standing issue with web site compatibility when browsing in Opera relates to something called "browser sniffing".
Browser sniffing is where web sites check what browser each visitor is using, and customize the site to a lesser or greater extent depending on what they find. The problem is it's very easy for the site to get it wrong. For example, a site may check for just "Internet Explorer" and "Netscape" and nothing else.
Sometimes a site will check for "Opera" and block it entirely! They do that because old versions of Opera (6 and earlier, now at least three years old!) had some problems handling scripts. That's a problem for recent versions of Opera because the problem web sites haven't updated their scripts for years. Again, the relatively few people using Opera provide little incentive to update, even though the updates are simple and often free.
A known problem with sites that do check for Opera, is that they check for exactly Opera version 7, and not version 7 or later.
In Opera 9+ you have site specific preferences (right click "Site preferences...") --> named SPP.
With those settings you may want to make Opera understand some web sites even better (as an example you may want Opera mask as IE for better reading a site in question you may try 'right click - site preferences' (SPP) > network > browser id > mask as IE).
In Opera 9+ you may want set site specific cookie setting as well like for instance some special Yahoo & Google sites like web mail.
Opera Software have created a solution to this problem: changing how Opera identifies itself on a per-site basis. Using a database of web site addresses, Opera will automatically change its identity as required, letting you surf hassle free.
The database is updated every week by Opera Software, simply select Help->Check for new release and the latest database will be downloaded.
If you find a web site that isn't working, try changing Opera's identity yourself by pressing F12 and selecting a different identity. If that doesn't work (or even if it does) then you can select Help->Report a site problem. By describing the problem (if you solved it or not) Opera Software can investigate and determine if the problem can be solved by an updated database.
One of the most technically interesting new features in Opera 8 is UserJS. This allows a set of scripts to run on every page you visit. It's possible to rewrite web pages "on the fly"!
There will be cases where even all the above isn't enough. Sometimes the web site is smart enough to detect Opera no matter the identity presented. Sometimes the problem won't be related to the browser identity at all, but instead some obscure scripting issue. The site could also be looking for a feature that Opera hasn't implemented. It could even an Opera bug!
In those cases, the site should be reported to Opera. If the problem is an unsupported feature, each report is a vote for that feature to be added. If the problem is a bug, Opera will add it to their "fix" list.