Lately I had a lot of issues with converting three server core systems to a full GUI version of the Windows Server 2012 R2.

I have tried following stuff the would not work for me with the following error message (The source files could not be found. Use the “Source” option to specify the location of the files that are required to restore the feature. For more information on specifying a source location):

1. mounted the Windows image to the drive and tried installing feature via Dism /online /enable-feature /featurename:ServerCore-FullServer /featurename:Server-Gui-Shell /featurename:Server-Gui-Mgmt (this should download the files from the windows update but it would not work)
2. mount the windows image to the folder on some drive and then pull source from there the process includes following:
   – create a folder to mount the windows image mkdir c:\mountdir
   – determine the index number I need to use from the source of image Dism /get-wiminfo /wimfile:<drive>:sources\install.wim
   – Mount the WIM file using: Dism /mount-wim /WimFile:c:\sources\install.wim /Index:4 /MountDir:c:\mountdir /readonly (index can change in your environment depending on the output from the previous command in mine it was number 4 Datacenter
   – start the powershell in cmd and run: Install-WindowsFeature Server-Gui-Mgmt-Infra,Server-Gui-Shell –Restart  –Source c:\mountdir\windows\winsxs

The problem is mine windows installation differs from the image I have supplied to the dism. There is no way of me knowing what has been patched on each server and what image i need to supply. It probably needs to be the same patch level of the image and the windows server so the sources from the WIM image work.

After playing with this for the whole day the following command did the trick for me:

Dism /Online /Enable-Feature /FeatureName:Server-Gui-Mgmt /All /Source:\\[server fqdn with GUI]\c$\Windows\WinSxS /LimitAccess

This was unbelievable. The windows server installation wouldn’t accept files from the online source, it wouldn’t work from the same image where I installed the server but it would work from the server in the same domain that had the GUI installed and probably it was os the if not the same but similar patch level. After this wizard has finished and I was able to get the server manager and then to install the full GUI on the end. One more nonsense battle with the Windows server was won by converting a server core to full GUI :-)