I have heard from a few customers (inside and outside of Microsoft) who have had problems uninstalling previous beta versions of SQL Express via Add/Remove Programs or via the cleanup tools we have released (located here and here).  These customers have seen unexpected errors in the datastore related to the actions named RestoreSetupParams and/or Write_CommitFlag.  The exact error message states that setup is unable to write property into the cache: IsClustered and unable to write property into the cache: flagCommit.

I haven't narrowed down the exact sequence, but these uninstall errors are caused by uninstalling beta versions of SQL 2005 and/or VS 2005 in specific orders.  The officially recommended uninstall order for these products can be found at this location.  However, this order is not enforced via the Add/Remove Programs control panel and it is pretty easy to overlook the readme and uninstall in alphabetical order or some other random order and get into this state.

If you encounter either or both of the above error dialogs, you can use the following steps to resolve the errors:

1. Download and run msiinv.exe using the instructions in this previous blog post
2. Look at the output from msiinv.exe in a text editor such as notepad and locate each of the products that are installed that have SQL 2005 in the name
3. Click on the Start menu, choose Run and type cmd
4. For each of the SQL 2005 product codes found in the msiinv.exe output, run msiexec /x {Product Code} from the cmd prompt - this command will likely generate the same errors shown above but it is good to run it just in case
5. Download the smartmsizap tool
6. For each of the SQL 2005 product codes found in the msiinv.exe output, run smartmsizap.exe /p {Product Code} from the cmd prompt

After running smartmsizap to cleanup each of the SQL 2005 products left behind on your machine, you should be able to successfully install later builds of SQL Express and/or VS 2005.

<update date="11/26/2005"> Added text descriptions of the error messages to make it more likely that this blog post will be found from internet search engines because I have heard from a lot of customers who have run into this error but not found this blog post. Also modified the uninstall instructions to use the smartmsizap tool that I had not yet written at the time that I originally wrote this blog post. </update>

<update date="4/14/2009"> Fixed broken link to the smartmsizap tool and removed broken image links. </update>

<update date="8/27/2010"> Fixed broken link to the VS 2005 uninstall instructions and the TTool.zip tool. </update>