We recently upgraded an MVC3 application to MVC4 and .Net 4.5. The upgrade was done by creating a new MVC4 site and adding all the controllers etc back in, manually.
The site was deployed internally to a win2008 R2 64 bit server, on which we installed .Net 4.5.
When we browse to the web site with IE8 or IE9 the application works well for a while as we navigate through various pages, including standard views, partial views, popups, paged lists etc.
At some point we end up going to a page in the site (any page, complex or not) and IE8 and 9 both just sit there for a long time (usually 1-3 minutes and displaying the page loading progress bar) eventually they both show the page as requested. Often the same behaviour occurs on the following few pages and then magically comes right (for a while)
If we browse to the same web site in Chrome, Ie10, Safari, FF at there are no issues at all. If we browse to the web site with one of these browsers from the same machine while the ie8/9 are "loading" then we can still access the site quite happily without any issues.
A check of task manager memory and performance on the client, web server and database server shows almost no CPU usage and no increased memory usage while this is happening. It is almost as if the browser is just taking a tea break. Fiddler shows nothing unusual either.
It should be noted that as this is an SAAS application we are managing multiple databases through the same site and these are configured into the users session state based on an incoming url in the web site bindings. Having said that as far as we can tell, the session state is remaining intact. a) The browser does eventually return with the expected data, b) there are no recycling events recorded in the event log (in fact there are no events at all around the time this issue occurs)
Application pool is set to framework 4.0.30319, integrated, enable 32bit, max worker processes = 1
We reverted the web site on the server back to the original MVC3 implementation and still retained the .net4.5 install on the web server. This now exhibits the same fault as the mvc4 site.
We re-imaged the server to a state before the .net4.5 was installed, ran the MVC3 site and everything operated again as we would expect. Repeating the install caused the same problem again.
It is almost like the .net4.5 install on the server has caused some problems for the IE8/9 browser. Back to fiddler again, which shows different host headers for the different version of .Net, but that seems to be the only difference.
Whilst we would love to be able to tell the user's not to use ie8/9 that is not practical, so now we are completely stuck.
Any help / ideas will be appreciated. Thanks.
