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I recently upgraded an ASP.NET app to .NET 3.5 and switched to the newer version of the ASP.NET AJAX library.

In FireFox and IE7, everything works great, in IE6, anything that would perform a callback (Partial Refresh, or calling a PageMethod/WebMethod) throws an error:

Object Doesn't support this property or method
Line: 5175
Char: 9

Is there a known compatibility issue with .NET 3.5 and IE6?


I attached a debugger to IE6 and was able to find the exact line it is breaking on:

 this._xmlHttpRequest.open(verb, this._webRequest.getResolvedUrl(), true /*async*/);

It appears that IE6 is denying the permission to do "open". This is not a cross-site request, so I am puzzled. This site is currently running on a fake hostname mapped to a local server, and not on an actual domain, but I don't think that should make a difference.

EDIT: I added a bounty, this bug is still driving me nuts...HALP!


Solution found!

This forum post made me curious enough to search for MXSML, and sure enough, there it was, a typo in the framework library.

MsXML was typed as MXsml.

Of course, when dealing with assembly scripts, you can't do much to fix them, but I installed SP1 hoping that they were corrected there. They were...So, if you have this issue, install .NET 3.5 SP1 and it will go away.


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3 Answers 3

up vote 2 down vote accepted

How are you testing in IE6? I have come across several javascript errors when you using anything but a clean install of only IE6 in conjunction with the asp.net ajax libraries. (ie. the asp.net ajax libraries don't support multiple installs of IE, or even IETester)

It is something in the IE security model that makes things go haywire when multiple version's of IE are used. You'll find that cookies won't work right either in anything but the "installed" version of IE on the system you are running.

You may also look here for some more information on multiple IE installs. If found the comments to be particularly helpful!

UPDATE I was able to dig, this up in the asp.net fourms. That's the only other thing I could find. May not be too be too helpful, but it at least sounds about like what you are hitting.

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Single install of IE, verified on several test lab machines too. –  FlySwat Mar 9 '09 at 16:55
Hmm, well that does make things interesting.. just found one resource though. Added it to my answer –  Joshua Shannon Mar 9 '09 at 17:06
The forums link points to the same issue I am having...MXSML instead of MSXML. I am reinstalling the framework, hopefully that corrects the issue. –  FlySwat Mar 9 '09 at 18:18
Upgraded to SP1 and that typo is fixed, as well as it now works. –  FlySwat Mar 9 '09 at 19:13

According to MSDN IE6 is supported. Make sure that the Internet Zone in the Security Zones settings are set to Medium.

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I've even tried "Low". –  FlySwat Mar 4 '09 at 21:41
The only other thing I'm turning up is that there could be a javascript function with the same name as a control on the page. –  notandy Mar 4 '09 at 21:55
that sounds quite possible - namespace pollution can be a real problem on large apps –  annakata Mar 9 '09 at 16:58

Another one from the asp.net forums


Could be caused by different versions of the XmlHttpRequest object

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