问题
I have a webservice for ajax cascading dropdownextender. Which is working fine. But suddenly it raised a exception. MethodError 500. What is this exception.
Can any one resolve this exception. Please post a possible solution. Its an urgent requirement.
回答1:
A 500 normally just means that there was an exception in the server side code, which wasn't handled.
You'll need to trace/log through the webservice to see what is failing.
You're almost certainly looking for a .Net code error.
回答2:
500 errors are internal server errors.
The web service most likely had an unhandled exception thrown somewhere, causing IIS to return this error.
You need to look in your event logs to see what the actual exception was. These are exceptions thrown by ASP.NET and can be any sort of exception.
回答3:
Are you using a database query for your cascadingdropdown? If you are then check the results of your SQL statement. Most likely your query returns or has a null value in it.
回答4:
This error may occur if you are built a .Net Core Web App and too if you decided to build the server-side scripting in the WebService.asmx.cs
I have found the error to occur while using the .NET Core Web Application.
ASP.NET Core Web App comes prebuilt with the Web.Config file. You wouldn't need the WebService to connect to the Database (if you are trying to connect) because you probably would have created a connection string in that passes in the WebConfig file.
The source file will show different from the debug file. The debug file is the Web.Config file.
来源：https://stackoverflow.com/questions/8757127/method-error-500