We moved all our customers’ vms from Azure to our own cloud environment. In the process we had to downgrade the OS on our servers. Once the downgrade was complete in the CRM servers IIS was removed.
That was the first part of the problem to not allow us to run CRM. Once we figured out that IIS was missing we deployed that OS role and re-installed CRM 2015. After the installation we started getting the error HTTP Error 500.19 – Internal Server Error.
After a lot of research we found out that there’s a section in the CRM server web.config related to the URL Rewrite component. That makes the installation required in any CRM deployment.
What happens is that URL Rewrite is no longer available with Windows 2012. We had to manually download the component from Microsoft’s IIS web site and deploy it. Once that was done CRM started loading immediately.