Opera cannot be found among the default apps for HTML
Here is the story: I had Opera 12.XX and recently I upgraded to Opera 24.XX however after a few hours I didn't like it so I downgraded back to Opera 12 to be specific to the latest being Opera 12.17.
With this back and forth, now my Opera 12.17 cannot be found among the default apps to choose for HTML; see picture here: https://www.dropbox.com/s/4132iquhilc6hel/Screenshot 2014-09-16 11.12.55.png?dl=0
That is really weird... Should be back if you reinstall O12 tho, but it might be a pain in the arse to do
I will try to do a clean uninstall and reinstall back.
I am experiencing the same issue. I, as the original poster, am on Windows 8.x & earlier today I installed Opera Beta (to test it) & it asked me if I wanted to set Opera as the default browser but Opera Stable was not in the list (Opera beta was tho...)
I have IE11 set as my default for the "Metro conveniences" that come with setting IE as such. The only way I can set Opera Stable as the default browser is by navigating to "Control Panel\All Control Panel Items\Default Programs" through File Explorer... Fix it Opera?