Yesterday I had to place an InfoPath 2003 form on a MOSS 2007 farm. Everything seemed to be configured correctly. Accept after publishing I found the newly created form library and the form but when I tried to open it I was spoiled with a nice error message in a soft lightgray kind of way. It could have been red cause an error is an error people light gray or not it was not going to work.
Error Message
The form cannot be displayed because session state is not available.
Solution
The solution to fix this is simple, in the web.config of your site collections you find the SessionStateModule commented. just uncomment >> iisreset /noforce (so do this outside office hours 🙂 ) and you are up and running again.
To find this section just use ctrl+F and search on HTTPModules
Before
After
I have not checked it in SharePoint 2010 but I think it’s default already as it should be.
My SharePoint Scrapbook 