BlogEngine 3.3 after upgrade posts prior to April 2012 Display Home Page

Jun 14 at 5:11 PM
I've tried turning off custom errors and no error is happening. The post file exists. The archives page finds it.

The navigation on the right side of the home page lets you click on the month and then the posts for that month are list. But when you click on a link for one of the posts, it is not displayed. Rather the home page of the blog is displayed.

I upgraded from 3.1 to 3.3 and cannot for the life of me figure this one out. Any ideas?
Jun 14 at 6:03 PM
Additional info. I have examined the XML files for posts that work and for some that don't. I can find no material differences. I cannot find the GUID for a working post's file name anywhere in any other content. All posts, those new and those older, show up in the archives list and in the specific month list.
Jun 14 at 6:10 PM
I think I've found the problem. Now I need to find a solution. When I switched from dasBlog to BlogEngine, the <slug> went from using "+" to using "-" to connect words. So now that I have content that uses both, I need a way to allow both. Any suggestions?
Jun 14 at 8:31 PM
Found the problem and solution. To support slugs with a "+" rather than the "-" character, the following has to be added to the <system.webServer> section of your web.config file:
<security>
  <requestFiltering allowDoubleEscaping="true" />
</security>
Marked as answer by rtur on 6/15/2016 at 6:36 PM