VS 2017 : The security debugging option is set but it requires the Visual Studio hosting process which is unavailable
My solution (which contains a dozen projects) works perfectly in Visual Studio 2013.
In Visual Studio 2017, I can open the solution and compile it.
But if I start the debug, I systematically get this error message:
The security debugging option is set but it requires the Visual Studio hosting process which is unavailable in this debugging configuration.The security debugging option will be disabled. This option may be re-enabled in the Security property page. The debugging session will continue without security debugging
And then, nothing happens. Nothing starts.
For information, this is a solution with multiple startup projects (including a WPF project).
Edit : By disabling the option "Enable ClickOnce security settings" under Project -> Properties -> Security tab, it works.
Answer
Most likely, you have accidentally gotten the bit flipped to debug with ClickOnce security settings. Can you get the project properties for your app, go to the "Security" tab, and make sure to uncheck "Enable ClickOnce Security settings" or check the "This is a full trust application" radio button.