Possible problem installing Windows Phone Developer Tools CTP Refresh on a system with Silverlight 4 installed

Yesterday, I investigated a Windows Phone Developer Tools CTP Refresh installation issue on a colleague’s computer, and I wanted to describe what I found in case anyone else runs into a similar issue.

Description of the issue

Silverlight 4 was posted on Microsoft Update earlier this week, and I found that if this version of Silverlight is installed on a computer prior to running setup for the Windows Phone Developer Tools CTP Refresh, it will cause WPDT setup to fail while it tries to install Silverlight 4.  The error in the log file named %temp%\dd_install_vm_xcor_100.txt looks like the following:

[06/04/10,12:34:56] Microsoft Silverlight 4.0: ***ERRORLOG EVENT*** : Error code 1502 for this component means "The event log file is full."

Unfortunately, this error message is misleading, and it does not help to try to clear out your event logs in this scenario.  I narrowed this down further by having my colleague run the Silverlight 4 setup in full UI mode from the WPDT setup location.  When doing that, it displays an error message stating that a later version of Silverlight is already installed.

How to work around the issue

If you run into this error while trying to install the WPDT CTP Refresh, you can solve it by doing the following:

  1. Go to the Programs and Feature control panel.
  2. Locate the item named Microsoft Silverlight and uninstall it.
  3. Re-run WPDT setup.

This issue will be addressed in a future release of the Windows Phone Developer Tools.