Method Error 500/12031 In Ajax CascadingDropdown

If you are getting Method Error 500 or 12031 In Ajax CascadingDropdown, than you may have missed to include below mentioned line of code in code behind of your asmx (webservice) file

Add this line in webservice's code behind


It should look like this

[WebService(Namespace = "")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
public class CascadingDropDown : System.Web.Services.WebService {

It should fix the error
This also occurs if there is any error in your sql statements or webservice code, you need to check them as well

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Implementing Ajax Cascading DropDownList in GridView with databse in ASP.NET

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Anonymous said...


raphaww said...

OMG thanks a lot!

Anonymous said...

Thanks you only solved my problem

Look and Learn said...

method error 500 in ajax cascading dropdown i use
also i got that error

Anonymous said...

thanks... @Satish

Anonymous said...

That was easy, thank you!

Anonymous said...

Method error 500 still persist..Please help

hemalisachdev said...

Still that error is there Method Error 500 Pls help...

@fadrianamv said...


Anonymous said...

Thanks it's working

Anonymous said...

still got method 500

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