IIS 7.5, ASP.NET MVC. HTTP error 500 (internal server error), but debugging does not enter the background, the browser only reports 500 errors

Bugs, such as:
IIS 7.5, ASP.NET MVC. HTTP Error 500 (Internal Server Error) uploadify uploads images, the browser only reported 500 errors, the progress bar does not move, but debugging does not enter the background
After several days of searching, I could not debug the source of the error. I also wondered whether the maximum byte limit of the upload was limited. However, I finally found the prompt of foreign gods under Google and determined that it was this error.
& lt; The httpRuntime requestValidationMode = “2.0” maxRequestLength = “100000”/& gt; The configuration file adds a maximum byte limit

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