Failed to start the application because the application configuration is incorrect,

From. in a WCF project migrated from NET 2.0, an error is reported when it is enabled with vs2010 and upgraded to 3.0 or 4.0. the application cannot be started because the application configuration is incorrect, check the configuration file to find possible errors. I checked it online and said that the dynamic link library could not be found. Copy the DLL in the vs installation directory to system32, I did not respond, but the problem persists.

I decided to find the problem by myself. I checked the error again, for example:

The last sentence "See Application Event Log"

The Event Viewer is immediately opened as follows:

A prompt is displayed.

Because I have three projects for migration, only one project cannot be compiled.

Compare the two app. config.

Here I think you should understand, because this project has a xmlns = "http://schemas.microsoft.com/.NetConfiguration/v2.0"> limitation.

If this constraint is removed, it should be OK. My problem has been resolved.