In ASP.NET you can create Global.asax in two ways - with code behind file or without (like script). So it's important what Global.asax file you have, because if it is with a code behind file is normally to be built in order to work.
However, if you want to have a dynamic Global.asax you should remove the code behind file (Global.asax.cs) and edit Global.asax file to something like this example:
<%@ Application Language=
sender, EventArgs e)
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