I was trying to create a new Web Application on my SharePoint farm and as soon as it was created, I got the following error:
I googled, fiddled, interogated logs. All to know avail.
Eventually, in desparation, I decided to uninstall SharePoint and try again.
Unfortunately, this time I got the above error as soon as I created the Central Admin Database.
So what was going ON?
In my case, I found that this was an issue with the Supplemental .Config file that I had created.
I had never created one of these before but, as per Microsoft Best Practice, the SharePoint Web.Config file should not be editied directly. Changes should be made in a custom file, stored in %CommonProgramFiles%\Microsoft Shared\web server extensions\14\CONFIG
I took a loko in this directory and what should I see but not only my Supplemental file, but a very suspicious looking file called "Webconfig.rs".
So, I removed my own Supplemental file and it resolved the issue.
I haven't figured out the exact cause of this issue yet. I suspect that as the Web Config file is updated when a new Web App is created was getting muddled. Most probably caused by some malformed XML in my own file.
The good news is that the problem is fixed and I can continue my install.