One error which strikes fear into the hearts of IT professionals is the dreaded “Unknown Error 0x800F082F” which sometimes occurs when attempting to install a service pack, or other Windows component. Indeed, there is a significant number of posts on the internet where people have been unable to get this issue resolved; Aside from the ever-faithful “Reinstall Windows” solution.
I personally abhor the prospect of reinstalling the Operating System on any computer to fix an issue which doesn’t actually stop the computer from doing its day-to-day job.
I myself have recently spent weeks attempting to resolve this issue on an SBS server. For those of you who are not aware, Microsoft Windows SBS does not allow you to perform a “Repair Install” like you can on Windows Vista or 7. Furthermore, you cannot install a new SBS system into an existing domain. Therefore, reinstalling Windows was not an option for us as it would have required a week of downtime in order to recreate Domain Accounts, Exchange Mailboxes, etc, etc. (Restoring from a backup would have brought the problem back)
As you may or may not know, all Windows Updates and core system features are installed through the “Windows Modules Installer” service. As such, every action performed by this service is logged in a file, located in “C:\WINDOWS\LOGS\CBS\CBS.LOG”
Now, when you see 0x800F082F appear when installing Windows Updates, Server Roles, or Service Packs, the CBS.LOG file will generally throw an error that looks like this:
Exec: Cannot finalize session because an exclusive session is pending. [HRESULT = 0x800f082f - CBS_E_EXCLUSIVE_WOULD_MERGE]
What this actually means, is that there is another action pending that requires the exclusive attention of the Windows Module Installer service and it cannot continue until that process has completed.
Now, I had spent many hours attempting to resolve this issue myself and tried many proposed solutions including, but not limited to:
- Running the Windows Update Readiness Tool (KB947821).
- Resetting the Windows Update Components (KB971058).
- Renaming the “SoftwareDistribution” folder.
- Running SFC /SCANNOW to check for system file corruption.
- Running DISM to ‘Roll Back’ or fix failed updates.
None of these solutions worked. Finally, hanging my head in defeat, I called Microsoft for support. I spent two weeks liaising with Microsoft. Their support personnel, though helpful and knowledgeable were unable to resolve the issue. They made registry changes and replaced files all relating to the Windows Update system, but ultimately, even they said “Reinstall your Operating System”.
Now, if being in IT for 20 years has taught me anything, it’s sheer blockheaded persistence, so I thought I’d give it a final go before resigning myself to a few lost weekends rebuilding a server from scratch.
I decided to focus on the registry as I know that in previous versions of windows, there was a registry entry that told the computer that a reboot was necessary and not to do anything else until that was done, so I thought “why should this be any different?” After some searching and hunting, I found what I was looking for:
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Component Based Servicing\SessionsPending] "Exclusive"=dword:00000004 "TotalSessionPhases"=dword:00000001
So, as a educated guess more than anything, I changed these settings to:
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Component Based Servicing\SessionsPending] "Exclusive"=dword:00000000 "TotalSessionPhases"=dword:00000000
Then I rebooted the server. After the reboot, which took longer to perform than usual – which to me was a good sign, I attempted to run a Windows Update….
It worked!
As you would imagine, I was beside myself with joy at the fact that I no longer had to do a server rebuild. I reviewed the CBS.LOG file, and all the pending updates had processed successfully, and I was finally able to add the Server Role I needed and also installed Service Pack 1.
Needless to say, I am one very happy camper presently, and I sincerely hope my post here helps others.
*Please note that this fix involves making changes to your system registry. If you are not confident with the system registry, seek assistance from a trained professional. As with any foray into the registry, be sure to have a good backup handy.