I was following Quick Installation Guide available here to uninstall my fresh Sitecore 9.1 instance.

It says in chapter 4.2. Uninstall the XP Single topology this:

To uninstall any of the Sitecore XP topologies, change the Install-SitecoreConfiguration cmdlet to Uninstall-SitecoreConfiguration.

For example: Change Install-SitecoreConfiguration @XP1Parameters *>&1 | Tee-Object XP1- SingleDeveloper.log to Uninstall-SitecoreConfiguration @XP1Parameters *>&1 | Tee-Object XP1- SingleDeveloper-Uninstall.log

Run the script and the topology is removed.

I have done exactly that:

enter image description here

This is the exact code:

#Install-SitecoreConfiguration @singleDeveloperParams *>&1 | Tee-Object XP0-SingleDeveloper.log

# Uncomment the below line and comment out the above if you want to remove the XP0 SingleDeveloper Config
Uninstall-SitecoreConfiguration @singleDeveloperParams *>&1 | Tee-Object XP0-SingleDeveloper-Uninstall.log

I have uncommented what was needed to and commented what I had to.

But getting this error:

Uninstall-SitecoreConfiguration : No registration found for extension 'RemoveSQLDatabase' of type 'Task'. At C:\ResourceFiles\03_UninstallSitecore_XP0-SingleDeveloper.ps1:77 char:1 + Uninstall-SitecoreConfiguration @singleDeveloperParams *>&1 | Tee-Obj ... + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + CategoryInfo : NotSpecified: (:) [Write-Error], WriteErrorException + FullyQualifiedErrorId : Microsoft.PowerShell.Commands.WriteErrorException,Install-SitecoreConfiguration

[TIME] 00:00:01

MapTasks : No registration found for extension 'RemoveSQLDatabase' of type 'Task'. At C:\Program Files\WindowsPowerShell\Modules\SitecoreInstallFramework\2.0.0\Public\Install-SitecoreConfiguration.ps1:453 char:28 + ... sksConfig = MapTasks -InputObject $rawConfig -TasksToExecute $tasksTo ... + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + CategoryInfo : NotSpecified: (:) [Write-Error], WriteErrorException + FullyQualifiedErrorId : Microsoft.PowerShell.Commands.WriteErrorException,MapTasks

This is how it looks in Powershell in full length:

enter image description here

Any thoughts?

I have already run Update-Module SitecoreInstallFramework to have up to date SIF.

3 Answers 3


You are missing the SQLServer module.

Either run the prerequisites.json file which will install that and any missing prerequisites or:

Install-Module -Name SQLServer if you are just missing the SQL server module.

  • I have already run prerequisites.json during installation. I have received this error when running command suggested by you in your answer: PackageManagement\Install-Package : A command with name 'Decode-SqlName' is already available on this system. This module 'SqlServer' may override the existing commands. If you still want to install this module 'SqlServer', use -AllowClobber parameter. At C:\Program Files\WindowsPowerShell\Modules\PowerShellGet\\PSModule.psm1:1772 char:21..... Dec 3, 2018 at 8:51
  • 1
    My guess is that you have SQL installed locally on your machine? This isn't a problem, however an old SQL module called SQLPS will be there that causes that error. I would suggest you run two things. Your PowerShellGet module is out of date, so run "Update-Module -name PowerShellGet" and then "Install-Module -Name SQLServer -AllowClobber -Force" which will override the SQLPS module. Dec 3, 2018 at 9:01
  • Thanks for helping me Richard. At the end I have run prerequisites first, close Powershell command window and rerun instainstall script. Seems that uninstall script did not recognized new SQLServer module ... Dec 3, 2018 at 9:15

I have fixed this by:

  1. Rerunning Install-SitecoreConfiguration -Path .\Prerequisites.json . Not sure why first run was not successful. Could be that I have forgotten to run it before installing first Sitecore 9.1 instance... Can't remember precisely as it was during release night :)
  2. Closing Powershell command prompt (to make changes / updates in step 1 take in account)
  3. Rerunning uninstall ps1 script as mentioned in answer

Douglas Couto shared a different solution on his blog that has also worked for me. Some computers seems to have access right issues.

When calling the SIF command, use the ByPass ExecutionPolicy.


  • powershell -ExecutionPolicy ByPass Install-SitecoreConfiguration -Path .\Prerequisites.json
  • powershell -ExecutionPolicy ByPass Uninstall-SitecoreConfiguration @XP1Parameters *>&1 | Tee-Object XP1-SingleDeveloper-Uninstall.log

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