OM12 Operations Manager Web Part Reinstall In SharePoint Fails

Bumped into this issue. Somehow the Operations Manager Web Part wasn’t properly installed so it had to be removed. Easily done, since there is a well documented procedure for it. The uninstall went fine.

So it was time to reinstall it and this is the error I got:

But this is the kind of error message I like since it tells me exactly what’s wrong: ‘…ERROR: Remnant files exist in the GAC, please remove and re-run the installation script...’ and on top of it, how to remedy it:

To remove these files it is necessary to quit out of the Powershell. Stop (SharePoint 2010 Timer) service (net stop SPTimerv4). Stop (Internet Information Services) (net stop w3svc). Then manually delete the files listed from: C:\Windows\Assembly. Then manually restart the (Sharepoint 2010 Timer) service (net start SPTimerv4). Then manually restart the (Internet Information Services) (net start w3svc or II SReset). Remnant files found... Microsoft.EnterpriseManagement.SharePointIntegration.DLL

Stopping both services went fine (from an elevated cmd prompt!) but locating the file Microsoft.EnterpriseManagement.SharePointIntegration.DLL  in folder C:\Windows\Assembly wasn’t a success.

But the good old cmd prompt came to the rescue: the command
dir /s %windir%\Assembly\Microsoft.EnterpriseManagement.SharePointIntegration.DLL told me exactly where that file resided:

Now it was easy to remove that file, restarted both services I stopped earlier and reinstalled the Operations Manager Web Part as documented. Now the deployment run without any issues at all.