Cannot Install Windows Service Pack 1. Error Code: 0x800f0826


New Member
When I try to install W7SP1, I get an error message after it tries to install after restarting after having downloaded it in Windows Update.
It's error code 0x800f0826. IT used to be 0x80071a9, but I fixed that I think.

Note: My laptop does not have a built in disc reader, because of its design, nor did it come with any W7 CD's.


Excellent Member
Microsoft Community Contributor
You might start by checking this Microsoft site. Possibly it will lead you do a solution. Since the error has changed possibly it got past one problem and went on to another, but the link might help anyway. I will look for a link to the other error.

If you want, you might open the WindowsUpdate.log located in the Windows directory and copy the last day or two of the log and put it in a text file and attach using the paperclip. Maybe someone will see something that might help find a cause for your problem.

Edit: I found this link, but it does not specifically mention SP1. There have been several folks having problems that had previous failed updates for earlier attempts prior to SP1. The senario seemed to be a prior update would fail at first but complete the install later. It appears the system got out of sync with the current situation and would not install SP1 until the earlier updates had been completed. In some cases it may have taken a couple of days for all the required updates to get sorted out.
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Excellent Member
Microsoft Community Contributor
The logs show the install has completed successfully but an error after reboot many times. This log does not give the reason for the failed attempts except for the error you mention. Some site suggest this is a prior install needed type message. Have you checked the Update history and looked for any failed updates, even if they succeeded later?

I found this thread where this person seems to know what updates are causing the problem, so you might check yours.

Have you done anything like renaming the SoftwareDistribution folder? Do you have plenty of room on your C: partition?

You might go to the Windows\logs\CBS folder and look for the CBS.log. Copy it to the desktop so you can open it. Then look around the times of the failed installed attempts and see if there is anything regarding the following items.
2011-05-16 18:22:23:346
2011-05-16 18:51:16:351

References to search for:


I think I would hide the SP1 update for a couple of days and let the other updates catch up. I would also turn off Automatic updates and check manually when you think about it. Maybe this would allow your system to repair whatever is causing the problem.

If you do have any updates that originally showed as Failed, I might think about uninstalling them and let them reinstall prior to unhiding SP1.

When you see a falloff of updates being offered , unhide SP1 and install it by itself.

Sorry I don't have a definite answer for your, but I haven't seen one item stand out relating to your situation.


New Member
Just a few questions before I do the steps mentioned in the thread.

1) Where can I download the updates for KB947821, KB976902, KB2487426 and SP1 (KB976932) in step 1?
2) How do I reinstall all W7 updates in step 3?
3) Does "deactivate all non-W7 processes" mean do a Diagnostic Start in step 7?

1) download KB947821, KB976902, KB2487426 and SP1 (KB976932)
2) separate PC from internet
3) reinstall all W7 updates and virus detection, deactivate windows defender
4) reboot
5) install KB947821, KB976902, KB2487426
6) reboot
7) deactivate all non-W7 processes from printer, screen …
8) install sp1
9) 100% configuration after reboot
For me it worked, some steps might be not necessary; there are probably other configurations, where it will be not successful


Excellent Member
Microsoft Community Contributor
Check for sites like this one to download. Probably do a search for that KB and download and it will show up on a Microsoft site.

Deactivating non-Windows processes is a diagnostic step in case something is messing with your system.

I have not installed anything but the SP1 manually, but instructions are on the site.

The first update you show (KB947821) has been downloaded in your log and was supposed to install this morning at 10. I have not checked the other ones.

Updates to install = 1
Title = Hotfix for Windows (KB947821)
UpdateId = {FA8E4375-08B4-4C89-885F-095BCE862FEB}.501
Bundles 7 updates:

Setting AU scheduled install time to 2011-05-18 10:00:00
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