How To Uninstall a Failed Windows Service Installation

August 16th, 2007

I’ve been doing a lot of work with Windows Services in VB.NET recently and, as a result, I’ve ran into a number of little tricks and traps in this area. I’m going to post these short, hopefully helpful, tips as I come across them.

One of these traps can happen when a service gets installed but gets stuck where you can’t completely uninstall it or install a new version. This can be caused by errors in your code, errors on the install itself, copying over an incorrect DLL or EXE manually, or other such things. When this happens it can be quite frustrating.

Here’s what you’ll see if you encounter this problem. When you try to reinstall the service, you’ll get a dialog that says, “The specified service already exists”, even if you’ve gone through the uninstall either from within Visual Studio or from the Add/Remove Programs control panel applet.

The program’s executables have been deleted from the installation folder but you’ll see your service app in the Computer Management Service console. You can’t seem to get rid of it. If you try to uninstall, you’ll see this message saying you can’t do it.

I’ve seen forum posts where people resorted to renaming their service after encountering this error. Some manually edited their registry to get rid of it. Still others wrote a quickie program or script using WMI to kill it. But, there is a much easier way to deal with it.

There is a command line utility in Windows called SC, short for service controller, that allows you to control Windows Services manually. One of the available commands is “delete”. This command deletes references to the specified service in the registry. Here’s the command syntax:

sc delete NameOfYourBadServiceGoesHere

Once you run this from the command window, the failed installation is cleared from the registry and you’re ready to do a clean install of your service program. Of course, you need to be careful about using this command in production environments. Also, you should have gone through the uninstall process first to remove the executables before executing this command.

Let me know if you found this tip helpful or if you have any other ideas or questions about it by leaving me a comment.

Entry Filed under: Tip Sheets

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