Wednesday, 14 May 2014

What is the difference between customErrors and httpErrors?

Both are used to define error handling for a website, but different software refers to different config elements.

customErrors are a legacy (backwards compatable) element, used by Visual Studio Development Server (aka. VSDS or Cassini).
httpErrors are the new element which is only used by IIS7.

The customErrors attribute is used when the .net code is throwing an exception (404, 403, 500 etc) and the httpErrors attribute is used when IIS itself is throwing an exception.

Errors section in web config is for providing custom http error handling approach there are two section, one customErrors inside the section system.web and another httpErrors inside the section system.webServer

customErrors : This section was in use before IIS 7 introduced, IIS 6 5 and before fully use this section for handling custom http errors according to http status code.
httpErrors : IIS 7 and later use this section as well as customErrors section to handle custom http errors based on their file extensions if requested page extension register with ISAPI dll (.aspx, ashx, .asmx, .svc etc) like index.aspx then IIS pick up setting from customeErrors section else it pick up setting from httpErrors (IIS 7 hosted mode must be set as integrated mood not classic)