Running two different versions of ASP.net will sometimes cause a conflict in IIS. One way to solve this problem is to have the website run in its own application pool. Here are ways of doing that with different applications:
Solution if you are using Helm:
1. Go to the domain and click on "Web Site Settings". In the Website Extensions section, change the ASP.net version to the desired version.
2. Check on "Application Pool Isolation"
Solution using IIS (without Helm):
1. Create a New Application Pool (you can name it the same as the website in question)
2. Specify the new application pool you just created for the particular website:
- Right click the website in question, select “Properties”
- Select “Home Directory” Tab; change the application pool to the one that was created.
Windows Event Viewer Application Error associated with problem:
"It is not possible to run two different versions of ASP.NET in the same IIS process. Please use the IIS Administration Tool to reconfigure your server to run the application in a separate process."
Article ID: 33, Created On: 12/8/2006, Modified: 10/20/2011