Old habits I guess. I had an upgrade go bad back in the 4.x era and have always just stuck to a manual web.config update procedure.

Anyway, I found these threads:
http://www.dotnetnuke.com/Resources/F...
http://www.dotnetnuke.com/Resources/F...
and more, which eventually brought me here:
http://www.mitchelsellers.com/blogs/a...

Since I am running IIS 7.5 Win2008 R2 and the Application Pool is set to .NET 4.0, then as suggested, I removed ",runtimeVersionv2.0" from all the handlers that had it. Now all is good.

I checked another DNN site that's running 5.6.2, and the web.config file does not have handlers with ",runtimeVersionv2.0".

My questions are:

• when and why was this added? 
• since this has been a known problem for over a year, why hasn't the DNN web.config been corrected?

 

Well... it's not that isolated. Just follow those links or do a search on LinkClick and runtimeVersionv2.0. I'm obviously not the first to run into this. I just happen to experience the problem through the Media module.

And, if the AppPool on your sites is not set to .NET 4.0, then you won't run into the problem. It's only a problem if you're using .NET 4.0.
So I don't think it's fair to say that it's an isolated problem. Unless by "isolated", you mean everyone using .NET 4.0.

I checked the release.config from a site that was upgraded to 6.0.1 and it contains runtimeVersionv2.0 on the following handlers:

• LogoffHandler
• RSSHandler
• LinkClickHandler
• CaptchaHandler
• UserProfilePageHandler

So it would seem to me that anyone upgrading to 6.0.1 and using .NET 4.0 will run into this issue.