Hello,
I have recently upgraded to "RadControls for WinForms Q2 2010 SP2" and since then, occasionally, I'm getting this exception:
AvlEnumerator:version mismatch
The relevant call stack is:
at Telerik.Collections.Generic.AvlTree`1.Enumerator.CheckVersion()
at Telerik.Collections.Generic.AvlTree`1.Enumerator.MoveNext()
What can be the problem? I couldn’t find documentation for it.
Thanks,
12 Answers, 1 is accepted

Under what circumstances and with what control are you getting this error?
I'd also advise upgrading to the latest Q3 2010 version as there are many good changes and fixes in this newer version.
Regards,
Richard

Do you need any more help with this? If so, just let me know. If the upgrade suggestion helped, please mark as answer.
Thanks
Richard

Unfortunately I didn’t find an elegant solution to it and it don’t want to upgrade at this monument because in the process of upgrading from “Q3 2009” to “Q2 2010” I had to make modification in my code and I don’t have time to do so.
And back to our business, I didn’t found that this exception have any effect on my business logic and I couldn’t determine what cause it , so to avoid the exception (and I know that it’s ugly). I have done this:
catch (InvalidOperationException ex)
{
if (!(ex.Message == "AvlEnumerator:version mismatch" && ex.Source == "Telerik.WinControls"))
{
throw ex;
}
}
I’ll be happy to know if you have better solution to my or even explain what the exception means.
Thank,

Sorry to hear that you are still experiencing this issue. Please can you post a sample that replicates your issue and a description of how to replicate it and I'll do my best to replicate it and help out.
Thanks
Richard
We addressed issues related to the internal data engine of RadGridView for Q3 2010 and issues similar to the described one were resolved. Just like Richard said, you can give the latest version a try and if you still experinces any difficulties, please open a new support ticket and send us a sample application. This will allow us to investigate your specific scenario in detail.
Regards,
Julian Benkov
the Telerik team

I suggest you can replace "foreach" by "for".
Like Ren said the issue can be the foreach operator used in the case where you modify the collection of rows. In this scenario the solution is to use the for or while operators.
I hope this is helpful.
Julian Benkov
the Telerik team

I'll try to implement it and let you know...

I got error report from my application containing this Exception, but I can not reproduce it.
Im using the latest 2011.1 build of telerik winforms controls.

Are you looping over a collection and modifying it at any point? If so, then use the above suggested solution or use ToArray and loop over that.
Hope that helps
Richard

I will send it to the user, so he can test it for me ...

Please use 2011, it more powerful