asp.net - Understanding and Preventing AJAX Random Errors

Question

I've got a project that is about 5 years old. If it helps, it was written in VB.NET, and I seem to get fooled by the VB compiler swallowing errors a lot of times. I am trying to code around them, but the project is very big, and the AJAX code seems to never end.

Often when I start this project in the debugger, I get an error in some portion of the AJAX when the project tries to build.

I can build it again, the error is gone, and this project launches.

Here is the error I am looking at today:

The file name 'C:\Windows\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\reqtracker\cb9026c5\99d197a6\jg9oxyac.res' was already in the collection. Parameter name: fileName

Obviously, reqtracker is the project name.

I set breakpoints in the code behind to see what is going on, and often when I step through the code there will be AJAX JavaScript exceptions. I hit continue, because I don't really know how to troubleshoot them.

(I will attempt to add additional errors as I encounter them today.)

Are these errors that I should be addressing or are these random glitches from AJAX that AJAX developers just live with?

UPDATE: Another Error (pic form)

This error does not appear to be associated with any code, but it is an error all the same.

The Output Window has this text:

------ Build started: Project: C:\...\ReqTracker\, Configuration: Debug Any CPU ------
Warning: Unable to update auto-refresh reference 'ajaxcontroltoolkit.dll'. Cannot find assembly 'C:\Users\cp-jpool\My Projects\VS\Live\Program Files\Microsoft ASP.NET\Bin\AjaxControlToolkit.dll'.
Validating Web Site
Building directory '/ReqTracker/Scripts/'.
Building directory '/ReqTracker/'.
: Build (web): Object reference not set to an instance of an object.

Validation Complete
========== Build: 0 succeeded or up-to-date, 1 failed, 0 skipped ==========

Why is the compiler looking for AJAX in this folder?

C:\Users\cp-jpool\My Projects\VS\Live\Program Files\Microsoft ASP.NET\Bin\AjaxControlToolkit.dll

My Project is in this folder:

C:\Users\cp-jpool\My Projects\VS\Live\ReqTracker

Perhaps something is making AJAX or the compiler think the root folder is my project folder.

But why?

UPDATE: Another Error - this one in the JavaScript

I did not write this JavaScript, but there are still errors that are displaying in this _endPostBack method.

The problem is that something else is calling it, so I don't know how to get to the source of the calling routine to find out what is causing it.

Answer 1

Are these first chance exceptions?

If so, then they are generally harmless as a first chance exception is the debugger's "first chance" to handle the issue, if it does then no harm no foul. If the debugger cannot handle the issue, then it becomes a second chance exception that must be handled by your code or ultimately the runtime (read: yellow screen of death).

It would be easier to definitively say once you post actual exceptions you are receiving.