PENDING Some devices failing to install patch tuesday updates with error 0x8007066A

[kaibaker]

Here's a snippet from the client log:

<![LOG[1. Update (Missing): 2025-12 Cumulative Update for Windows 11, version 25H2 for x64-based Systems (KB5072033) (26200.7462) (3e1dea6e-9a62-4287-9767-a3afbea10525, 100)]LOG]!><time="15:00:53.237+360" date="12-16-2025" component="WUAHandler" context="" type="1" thread="7064" file="cwuahandler.cpp:1914">
<![LOG[2. Update (Missing): 2025-12 .NET 10.0.1 Update for x64 Client (KB5072928) (6992715c-116e-48cd-96a3-d132927f5a4d, 200)]LOG]!><time="15:00:53.239+360" date="12-16-2025" component="WUAHandler" context="" type="1" thread="7064" file="cwuahandler.cpp:1914">
<![LOG[3. Update (Missing): Windows Malicious Software Removal Tool x64 - v5.138 (KB890830) (9ba69000-b60b-4aae-96bb-a5506eb6ccfe, 200)]LOG]!><time="15:00:53.243+360" date="12-16-2025" component="WUAHandler" context="" type="1" thread="7064" file="cwuahandler.cpp:1914">
<![LOG[A top-level update (3e1dea6e-9a62-4287-9767-a3afbea10525) was not fully downloaded.]LOG]!><time="15:00:56.022+360" date="12-16-2025" component="WUAHandler" context="" type="3" thread="7064" file="cwuahandler.cpp:2288">
<![LOG[Failed to install updates. Error = 0x8007066a.]LOG]!><time="15:00:56.023+360" date="12-16-2025" component="WUAHandler" context="" type="3" thread="7064" file="cwuahandler.cpp:494">
<![LOG[Going to search using WSUS update source.]LOG]!><time="15:00:56.050+360" date="12-16-2025" component="WUAHandler" context="" type="1" thread="7064" file="cwuahandler.cpp:1687">
<![LOG[Synchronous searching started using filter: 'UpdateID = '3e1dea6e-9a62-4287-9767-a3afbea10525' AND DeploymentAction = *'...]LOG]!><time="15:00:56.050+360" date="12-16-2025" component="WUAHandler" context="" type="1" thread="7064" file="cwuahandler.cpp:1022">
<![LOG[Successfully completed synchronous searching of updates.]LOG]!><time="15:00:56.916+360" date="12-16-2025" component="WUAHandler" context="" type="1" thread="7064" file="cwuahandler.cpp:1068">
<![LOG[1. Update: 3e1dea6e-9a62-4287-9767-a3afbea10525, 100 BundledUpdates: 1]LOG]!><time="15:00:56.918+360" date="12-16-2025" component="WUAHandler" context="" type="1" thread="7064" file="cwuahandler.cpp:1792">
<![LOG[ Update: 2d948bef-d756-4956-a72f-6cd8045c5949, 100 BundledUpdates: 0]LOG]!><time="15:00:56.919+360" date="12-16-2025" component="WUAHandler" context="" type="1" thread="7064" file="cwuahandler.cpp:1792">
<![LOG[1. Update (Missing): 2025-12 Cumulative Update for Windows 11, version 25H2 for x64-based Systems (KB5072033) (26200.7462) (3e1dea6e-9a62-4287-9767-a3afbea10525, 100)]LOG]!><time="15:00:56.921+360" date="12-16-2025" component="WUAHandler" context="" type="1" thread="7064" file="cwuahandler.cpp:1914">
<![LOG[A top-level update (3e1dea6e-9a62-4287-9767-a3afbea10525) was not fully downloaded.]LOG]!><time="15:00:56.926+360" date="12-16-2025" component="WUAHandler" context="" type="3" thread="7064" file="cwuahandler.cpp:2288">
<![LOG[Failed to install updates. Error = 0x8007066a.]LOG]!><time="15:00:56.926+360" date="12-16-2025" component="WUAHandler" context="" type="3" thread="7064" file="cwuahandler.cpp:494">

 

[mangomatt]

I get the exact same. Happens on 30-40 of our 24H2 servers. Other servers are fine.

If I RDP into the server, open Software Center, and hit retry, installs without a problem. It doesn't seem to want to install it automatically.

 

[kaibaker]

I get the exact same. Happens on 30-40 of our 24H2 servers. Other servers are fine.

If I RDP into the server, open Software Center, and hit retry, installs without a problem. It doesn't seem to want to install it automatically.

This could be unrelated, but I found that every 24H2 device giving this error during updates had a corrupted component store. If you've gotten the error code 0x8007139F also, that points even more to component store corruption. Not sure if that's the issue, but I'm hoping to not see either 0x8007066A or 0x8007139F the next patch tuesday.

 

[mangomatt]

This could be unrelated, but I found that every 24H2 device giving this error during updates had a corrupted component store. If you've gotten the error code 0x8007139F also, that points even more to component store corruption. Not sure if that's the issue, but I'm hoping to not see either 0x8007066A or 0x8007139F the next patch tuesday.

I'll be sure to look out for that error next time I check logs.

I do want to mention that yesterday I turned on delta downloads for my 24H2 servers in the client settings. I did have it off for all servers. I set a mw last night for one of the servers with the issue. It did install during the mw. Going to see how the others do with delta downloads enabled. Could be coincidence but worth a shot.

 

[kaibaker]

I'll be sure to look out for that error next time I check logs.

I do want to mention that yesterday I turned on delta downloads for my 24H2 servers in the client settings. I did have it off for all servers. I set a mw last night for one of the servers with the issue. It did install during the mw. Going to see how the others do with delta downloads enabled. Could be coincidence but worth a shot.

One thing I do want to mention is that if you're using config mgr 2203 or later, delta downloads are enabled no matter what the client setting is set to.

SCCM Delta Download Is Enabled Ignoring Client Policy A Feature Change HTMD Blog

Let's SCCM Delta download is enabled ignoring the client policy. The client is always listening to port 8005. I have noticed a lot of chatter on this Delta

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