Sitecore install name not unique error

Question

I was trying to set up a Sitecore dev instance and I accidentally installed to the wrong path. It seemed like the easiest way to fix this was to delete the IIS instance, and remove the Sitecore DB's.

Unfortunately, I am now getting an error when I try to uninstall ("An error caused the Sitecore Installation Wizard to end prematurely"), and a "not a unique name" error when I try to install a new instance. What do I need to do to allow me to use the same instance name again?

Answer 1

So, @OptimizedQuery got me most of the way, until the Windows uninstaller stopped working. I then went into the registry and found the relevant entries here [HKEY_LOCAL_MACHINE\SOFTWARE\Sitecore CMS].

So, here is a list of steps.

1. Try the Sitecore installer and choose to remove the offending instance.
2. If that fails, manually remove it from IIS and delete the databases before using the uninstaller in the Programs and Features application.
3. If that fails, use regedit and delete the relevant children of [HKEY_LOCAL_MACHINE\SOFTWARE\Sitecore CMS]. Be sure to delete only the one with the matching InstanceName key.