I enabled SSL in Visual Studio 2015 in order to implement Facebook and Google login locally.
I changed the project URL in the Web tab of the project's properties to https://localhost:44300/ and decorated the controller with the RequireHttps attribute - ref @msdn.
Everything worked fine locally.
I reverted settings to HTTP to test something else and that caused me a problem when I tried to get back to HTTPS.
I found this SO question and tried almost every suggested solution.
Error detail:
Failed to register URL "url" for site "site" application "path". Error description: Access is denied. (0x80070005).