I've had the application installed, configured and working fine for months. Opened and ran it today, and all of a sudden I'm getting this error:

Error 1 It is an error to use a section registered as allowDefinition='MachineToApplication' beyond application level. This error can be caused by a virtual directory not being configured as an application in IIS. (web.config line 26)

Any body have an idea what's going on?

It's saying that you're trying to run it from a folder that isn't a virtual directory, or isn't marked as being an application in the IIS administration applet.

I wish it was so. It's running from a folder in the "C:\Inetpub\wwwroot\TheBeerHouse" directory, and is configured as a virtual directory in IIS.

Well, I figured it out.

I moved the project back to the file system, out of IIS.

From Visual Studio, opened the website only, not the entire project as I did earlier. Built the project and ran it successfully.

Still don't understand why it didn't work when I tried to open the entire solution, as a did before many times.