An exception of type ‘System.ArgumentException’

Question

hello expert,

 

An exception of type 'System.ArgumentException' occurred in System.Web.dll but was not handled in user code

Additional information: A route named 'MS_attributerouteWebApi' is already in the route collection. Route names must be unique.

 

in vs studio i cannot able to enter login n reg data successfully

 

https://www.youtube.com/watch?v=wWknX6eaWjg&list=PL7BTNHMTJY6jAH4-5X6vyD-qPqcMu2Q0u&index=3

 

i followed these step to step above link. but these files are missing a lot.

 

please help for me as i suggest u that when u watch that link then please u guide me for login n registration

 

i could not understand above link so u guide me for full angular 6 shopping