Windows 11 latest security patch is failing

Brian Burkill 20 Reputation points
2026-08-16T11:35:42.9866667+00:00

I have been on a lot of forums giving me fixes and completed every single one of them.
I followed the instructions to the letter. and they took a lot of time
I had my EFI file at 100 mb, and found Win11 needs more, so .using Partition Manager and trsnsferred 200mb to the EFI. IT STILL FAILED. I scanned my disks for errors, all OK and optimised them IT STILL FAILED. I used diagnostics and updated outstanding backups such as .net framework. IT STILL FAILED
I have been trying to fix this for 4 days. No luck.
The message I get is something to to with Parsing XML and sometimes the download fails.
I have used windows standalone installer. IT STILL FAILED.
The detail from my windows update history is :'2026-08 Security Update (KB5121003) (26200.9168)' and 'Failed to install on ‎16/‎08/‎2026 - 0x800705b9'

I am tearing my hair out with this as each attempt takes AGES.

Its Microsofts flaw, ao Can you send me a patch that will work

Windows for home | Windows 11 | Windows update

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Answer accepted by question author
DaveM121 928.6K Reputation points Independent Advisor
2026-08-16T12:10:13.05+00:00

If that update is continually failing, the best option is too pen the Settings App.

Go to System - Recovery.

Click the 'Reinstall Now' button in the 'Fix problems with Windows Updates' section, then wait for that process to complete, this process will not affect your files, settings or installed apps.

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