Global.asax Application_Error NullReference 异常

Question

Asp.net web Forms
in my Global.asax i'm handling Application error
i get Null Reference Exception Sender Global.asax
i debugged all functions inside non of them return error i'm sure it is from else where the problem that

Server.GetLastError()

Does not give information about the Error or the code giving the error

Answer 1

This can happen if you use incompatible code in Application_PostAuthenticateRequest or elsewhere in Global.ascx.cs.

See this answer for example: https://stackoverflow.com/a/21097374/1657610

If you have any code in Application_PostAuthenticateRequest or elsewhere in Global.ascx.cs, try commenting it out to see if the issue goes away. If it goes away, selectively reenable the code until the issue returns. In this way you can isolate the issue to one or two lines of code. At this point, either the reason may become obvious, or an internet search specific to that code is likely to provide the explanation.