Bypass ESU Longhorn

May I ask what are the reasons why Windows Update reports error code C8000266? Is the only reason that Datastore.edb has a maximum file size limit?

I'm asking this question because, before applying the ESU License Preparation patch, my freshly installed Windows Server 2008 SP2 can detect all patches before the ESU support start date, but as soon as I apply KB4474419, KB4493730 and activate the ESU license (either use TSForge or use BypassESU), Windows Update only reports error C8000266with no other results, no matter how many times I tried.

I did apply the Vista datastore.edb fix, but nothing changed afterwards. During the execution of the script, it prompted that the system denied it access to the wuaueng file, and I needed to manually change the owner of the file to Administrator to resolve this issue.

 

I have a guess, I wonder if it is correct?


By using MAS to view Activate IDs in Server 2008, I found that even if only the first of the two ESU patches (KB4575904) is installed, the Server-ESU-PA (Year 1-6) certificate will actually be introduced to the system.

And Server-ESU-PA (Year 1-6) is the ONLY ESU license that MAS has ability to activate, This is because MAS only “knows" PA key, but does not know key like ESU Year-1 or Year-2, and cannot construct a FakeCID.

In this case, even if I did not install the second ESU patch, Windows Update would detect ALL six years of patches and the system would be unable to process them.

Is the actual situation as I guessed? Thank you.

 

If you skip KB4575904 and go directly for the second ESU preparation package you won't need the datastore fix. The only downside is that the 2020-01 cumulative will pop up.

 

I searched the Microsoft Update Catalog and found that the descriptions of the two patches KB4575904 and KB5016891 both show that they replace KB4538484.

However, Microsoft does not seem to say whether there is a replacement relationship between the two patches KB4575904 and KB5016891.

I'm not sure what Microsoft intended. The Microsoft Knowledge Base page for KB5016891 only says that its prerequisites are KB4474419 and KB4493730, but it doesn't mention KB4575904.

 

I have been trying various methods for more than half a month to try to solve the 0xC8000266 problem when detecting ESU updates on Server 2008, but I have never succeeded.

I tried to use BypassESU-LH V8 on a Server 2008 system that has an activated ESU license. The reason I did this was that I thought the datastore.edb fix script that comes with it might solve this error, but in fact I didn't get any improvement.

I ran PatchWU.cmd separately, but it immediately exited because it didn't detect C:\Windows\System32\sle.dll. I think this may mean that when using BypassESU, it doesn't actually patch the logic related to datastore.edb.

 

I find it strange to be honest, I don't think Microsoft is unaware of the datastore.edb issue on Server 2008. Not sure if they have a patch specifically for Server 2008 PA running on Azure.

 

Well, I finally found the problem, and the answer is so simple:

After using the tool to patch wuaueng.dll and installing updates, a new version of wuaueng.dll in the updates replaced the original patched version on the system, which made the patch invalid.

It's unbelievable. If I hadn't accidentally seen in the folder that the creation date of wuaueng.dll changed from 2025 to 2022, I think I would never have found out the reason.

 

abbodi1406:

I just discovered your new BypassESU-LH-v8 tool for Windows Vista/Server 2008.

Where in my guide after step #20 do I deploy the new tool?

Can any of the 3 tools in steps #21 and #27 and #31 be eliminated?

I plan to do a start-to-finish test of my guide within the next week, and I would like to test it with the new tool.

 

Thanks for your advice.
I'm not sure what you're saying what I highlighted in bold text.

 

@abbodi1406, for me, BypassESU itself works well, but I get a 800B0109 error when updating .NET 3.5 (pointing out: only 3.5, not for 2.0, 3.0 or 4.6.2). I tried 2016-01 (official) and 2024-05 (unofficial) root certificate updates, but they did nothing. I don't even get WD definitions. How can I solve this issue? I have an Italian version of Vista, can that be the cause?

 

Also, I noticed that, starting from this month, my newly-made Windows Vista x64 ISO, once installed, asks for the 2020-01 CU, while I slipstreamed the 2025-05 CU into it, and it shows up in installed updates. Pretty strange. Maybe they changed the update, and disabled client installation of a number of packages? Will see what happens if I add both April and May CUs.

 

I assumed it was a script that you provided me with some time ago, but it may have come from someone else.
I honestly can't remember what fix the script provides (a Windows Update issue?), but it works, so I've continued to keep it listed in my guide.

 

Let's me tell. You need patched Net 3.5 and 4.6 from github @abbodi1406 , then Update from WU end success after installation. Net on Windows Vista still isn't fixed to install without problems.

 

To me i tried and with Mass and with that bypass esu LH Windows Serwer 2008 SP 2 and... Esus don't work after of course install updates before what that need. I saw that bypass only patch net and install suppressor on Windows Server 2008 SP 2. And I don't know if is bug. Next thing still C8000266 error on Server 2008. + Can't turn on TLS 1.2. i tried much tricks. someone can look that? Server 2008 standard SP 2 Polish edition.

 

Ok. So finally I putted all needed updates before esu to activate. Next activate with Mass TSForge ESU and activate Windows Server 2008. And and... Windows Update show C8000266 but by hands from msus to IE 9, Monthly Roll Up and Net Framework I installed success without scripts. Interesting. Net from July 2025 turned installer 4.7 and installed successful. All original from Catalog Update.
I don't know how fix C8000266 and Windows Update to work. Maybe bug in Mass. Or general problems .