Expanding RadTreeview node throws an error saying "error on callback"

[Deepak Siddappa]

In a webapge, We have a RadTreeview in the left pane, on click of any of the Radtreeview node, we are displaying the corresponding node content in the Radgrid.We have implemented few functionalities on the left and right click of the tree node. Our application would be used by lot of users at a given point of time.

On few instances the tree view would stop working. On expanding tree node say Folder 8.0, throws an error saying  "error on callback" and also on click of node (Folder 8.0) it will not show the corresponding content in the Radgrid.

Finally the folder 8.0 becomes unusable and to make it to work, we need to reset an IIS.
This is happening on our production environment and doing an IISRESET on the server is not feasible at all times.

What is this error? could you please give us a solution for this kind of problem.?

Regards,
Deepak

[Dimitar Milushev]

Hello Deepak,

If the server returns an unexpected result when a Node with ServerSideCallback is expanded, the "error on callback" error is thrown. This usually happens when there is an exception thrown on the server and ASP.NET returns an error page. You could either try attaching a debugger and catching the exception to see what's causing the problem or you could try using Fiddler or FireBug to inspect the server response and see what is the error page returned by the server.

Regards,
Dimitar Milushev
the Telerik team

[Syed Shuja]

same problem happened with me. there are two reasons for this:

1. There is an exception thrown from server side. 
2. DLL is corrupted 

My issue resolved after i updated the DLL even if it was of same size as old one. But it worked for me