I have a development install of DotNetNuke which has been working just fine for some time. This was a rebuild of a previous install which suddenly stopped working with "DotNetNuke Error". Not having time then to research the problem I went ahead and built a new development site. However today it happened again.
I had been working on a module and decided to create a new module using Chris Hammond's DAL2 template. I am not suggesting this caused the problem - I have tried to repeat the steps prior to the error without success. Visual Studio created all the files as per the template but when I went to the site I got the dreaded "DotNetNuke Error". This time I just had to find out why. The first stop was the EventLog table in SQL. This showed several errors. Of particular interest was:
DotNetNuke.Services.Exceptions.PageLoadException: Unhandled error loading page. System.Web.HttpParseException: The file '/DesktopModules/DDRMenu/Menu.ascx' does not exist. System.Web.HttpException: The file '/DesktopModules/DDRMenu/Menu.ascx' does not exist.
Checking the DeskTopModules folders shows me that the "missing" file does in fact exist. A websearch revealed little help until I found http://savian.blogspot.ie/2012/10/dnn-error.html I then removed the app pool and website from IIS and re-created the site. All seems well again :-)