I'm a tester for a small organization that creates web applications supporting the full gamut of IE versions.

One of my jobs is to ensure that the application works well in Microsoft Internet Explorer 6. To do this, I have a range of virtual machines and the IE6 testing suite.

The problem is, none of these environments seems 100% reliable. My virtual machines (VirtualPC and VirtualBox) have both thrown me errors that the developer team can't replicate - even when testing native installations.

We've had particular problem when developing for a client of ours who use IE6 exclusively. During field testing, we found our javascript-heavy functionality could throw up bugs in virtual machines which did not appear in real life. IETester can also throw false positives, especially with javascript.

Whilst I have never seen any false negatives, this has still caused us many headaches and wasted a lot of time on bugs that don't really exist.

My question is this: does anyone know if any particular virtualization environment achieves perfect IE6 'emulation', or do I have no choice except to hunt down an old WinXP IE6 box? Has anyone else experienced similar difficulties - if so, how did you work around them?

  • Testing under virtual machine has always worked well for me (at least the software/websites I was dealing with). I'm using VMware Workstation as virtualisation software (mostly because it has better snapshot management which is important for me). I cannot tell you which one is better though -- had no such issues with both VMware and VirtualBox.
    – LazyOne
    Aug 25, 2011 at 16:18
  • Do you know about IETester? This tool can access different versions of the IE COM-objects, and therefore the pages are actually rendered with the chosen IE. You seem to have done a lot for testing already, so maybe this is a bit undersized though. Aug 26, 2011 at 6:58
  • 1
    Microsoft have recently released official VMs for testing IE. microsoft.com/download/en/details.aspx?id=11575 Sep 27, 2011 at 16:17
  • Are you sure your virtual machines have the same software updates than the developer (not just the same browser version)?
    – Osvaldo
    Oct 1, 2011 at 8:57
  • Besides the initial install, Windows +-automatically downloads updates that fix some problems. Maybe your VM's haven't downloaded and installed this updates. You can try the official VMS for testing IE suggested by @paulmoriss In the web industry VM's are considered the best tool for testing.
    – Osvaldo
    Oct 1, 2011 at 19:32

1 Answer 1


A virtual machine running IE6 should run identically to IE6 running on a native machine. A way you could test this is to make a virtual machine out of the physical machine and then try and replicate the issue.

I would image the issues you are experiencing could be down to things like service packs and even hotfixes that could be installed on the machine.

Further to this IE6 handles JavaScript very poorly, which usually puts more stress on the machine, so if your dev is writing on IE6 on a machine with 2GB of RAM and you are testing on a VM with 512MB RAM you might find slightly different issues.

  • It's now moot, as we're using a physical box, but we believe our IE6 problems came down to certain VMs doing a poor job of coordinating threads for the IE6 render engine. Nov 1, 2011 at 14:47

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