Saturday, August 13, 2011

Having troubles with "Problems with *.gwt.xml file" due to user-agent issues? Possible fix.

When firing up my wife's new laptop the other day, I attempted to view the stats on one of my blogs hosted on, and was greeted with a rather bizarre error:

"Possible problem with your *.gwt.xml file. The compile-time user.Agent value (ie8) differs from the run-time value (safari). Expect more errors."

This was a bizarre error, particularly because it sounded like a configuration element from the server, not a local file. So, being the nosy developer I am, I started snooping. It took a couple of hours, but I think I understand the basic problem, and can provide at least a temporary fix.

This error originates from websites built with the Google Web Toolkit, which allows for a combination of Java and Ajax to build rich web applications. It's been around for a few years now, and most people don't even see it. However, with the beta and pending release of IE9, a problem arose with certain code that detects the type of browser you use to visit a particular site. My reading leads me to believe that the code to detect your browser has been overhauled because of IE9, and that overhaul has introduced a bug. It causes a plain-vanilla IE8 browser to be interpreted incorrectly as Safari.

The real fix, if I'm correct, is for the folks at Google to fix the newly introduced error into their user-Agent handling code. Until then, and given that you make registry changes to your system ONLY at your own risk, you might be able to get away with the following:

1. Determine if the Google ChromeFrame extension is installed. Go to Tools->Manage Add Ons, and look for "ChromeFrame BHO", and ensure it is enabled.
2. If it is present, and enabled, open Registry Editor (regedit), and look for the following value:


3. If it is present, add the following DWORD value with a default of 1:


4. Ensure all instances of Internet Explorer are exited, and then restart IE.

Try your site, and see if the error is gone.

Good luck!


  1. The registry hack worked great! However, I had to add a ChromeFrame folder and registry key DWORD.

  2. Thanks, it helps in Orkut too. :)

  3. Thanks! I'm having the same issue running IE 8 on XP. My coworker who's running Win7 64 doesn't have that issue though. But I'm sure there are a lot of people on XP -> IE8 so it would really suck if all these people can't view GWTs.