There will be a time, Windows Update failed in Windows 10 Operating System. You might trying clear somes SoftwareDistribution folders, restart related update services and run some OS fixes never successful.
I discovery this. I hope it might help you updating your Win 10 devices.
Symptom:
1. Windows update fail to get latest update.
2. Error message: "Your device is missing important security and quality fixes."
3. Sometimes, Windows update able to get the list of updates but fail to download.
Troubleshooting:
Run Get-WindowsUpdateLog in PowerShell. Got error like this:
2021/07/30 08:15:09.7884530 32308 46196 Agent Processing auto/pending service registrations and recovery.
2021/07/30 08:15:09.8084562 32308 46196 SLS Get response for service 9482F4B4-E343-43B6-B170-9A65BC822C77 - forceExpire[False] asyncRefreshOnExpiry[False]
2021/07/30 08:15:09.8084611 32308 46196 SLS path used for cache lookup: /SLS/{9482F4B4-E343-43B6-B170-9A65BC822C77}/x64/10.0.19042.867/0?CH=75&L=en-US&P=&PT=0x4&WUA=10.0.19041.867&MK=HP&MD=HP+ZBook+15+G5
2021/07/30 08:15:09.8085148 32308 46196 SLS Retrieving SLS response from server...
2021/07/30 08:15:09.8103223 32308 46196 SLS Making request with URL HTTPS://slscr.update.microsoft.com/SLS/{9482F4B4-E343-43B6-B170-9A65BC822C77}/x64/10.0.19042.867/0?CH=75&L=en-US&P=&PT=0x4&WUA=10.0.19041.867&MK=HP&MD=XX+xxxx+xx+xx and send SLS events.
2021/07/30 08:15:10.4598725 32308 46196 Misc *FAILED* [80072F8F] Send request
2021/07/30 08:15:10.4598821 32308 46196 Misc *FAILED* [80072F8F] WinHttp: SendRequestToServerForFileInformation (retrying with default proxy)
2021/07/30 08:15:11.9598228 32308 46196 Misc *FAILED* [80072F8F] Send request
2021/07/30 08:15:11.9598412 32308 46196 Misc *FAILED* [80072F8F] Library download error. Will retry. Retry Counter:0
2021/07/30 08:15:12.5498922 32308 46196 Misc *FAILED* [80072F8F] Send request
2021/07/30 08:15:12.5499032 32308 46196 Misc *FAILED* [80072F8F] WinHttp: SendRequestToServerForFileInformation (retrying with default proxy)
2021/07/30 08:15:13.1588271 32308 46196 Misc *FAILED* [80072F8F] Send request
2021/07/30 08:15:13.1588375 32308 46196 Misc *FAILED* [80072F8F] Library download error. Will retry. Retry Counter:1
2021/07/30 08:15:13.7414738 32308 46196 Misc *FAILED* [80072F8F] Send request
2021/07/30 08:15:13.7415019 32308 46196 Misc *FAILED* [80072F8F] WinHttp: SendRequestToServerForFileInformation (retrying with default proxy)
2021/07/30 08:15:14.3602191 32308 46196 Misc *FAILED* [80072F8F] Send request
2021/07/30 08:15:14.3602404 32308 46196 Misc *FAILED* [80072F8F] Library download error. Will retry. Retry Counter:2
2021/07/30 08:15:14.9470044 32308 46196 Misc *FAILED* [80072F8F] Send request
2021/07/30 08:15:14.9470259 32308 46196 Misc *FAILED* [80072F8F] WinHttp: SendRequestToServerForFileInformation (retrying with default proxy)
2021/07/30 08:15:15.5479151 32308 46196 Misc *FAILED* [80072F8F] Send request
2021/07/30 08:15:15.5479309 32308 46196 SLS Complete the request URL HTTPS://slscr.update.microsoft.com/SLS/{9482F4B4-E343-43B6-B170-9A65BC822C77}/x64/10.0.19042.867/0?CH=75&L=en-US&P=&PT=0x4&WUA=10.0.19041.867&MK=HP&MD=HP+ZBook+15+G5 with [80072F8F] and http status code[0] and send SLS events.
2021/07/30 08:15:15.5479390 32308 46196 SLS *FAILED* [80072F8F] GetDownloadedOnWeakSSLCert
2021/07/30 08:15:15.5481256 32308 46196 SLS *FAILED* [80072F8F] Method failed [CSLSClient::GetResponse:625]
2021/07/30 08:15:15.5481341 32308 46196 Misc *FAILED* [80072F8F] Method failed [CSLSEndpointProvider::GetWUClientData:2275]
2021/07/30 08:15:15.5481374 32308 46196 Misc *FAILED* [80072F8F] EP: get client data
2021/07/30 08:15:15.5481420 32308 46196 Misc *FAILED* [80072F8F] Method failed [CSLSEndpointProvider::GetSecondaryServicesEnabledState:1689]
2021/07/30 08:15:15.5481479 32308 46196 Agent *FAILED* [80072F8F] Method failed [CAgentServiceManager::DetectAndToggleServiceState:2910]
2021/07/30 08:15:15.5481567 32308 46196 Agent *FAILED* [80072F8F] Failed to resolve federated serviceId 9482F4B4-E343-43B6-B170-9A65BC822C77
2021/07/30 08:15:15.5481671 32308 46196 Agent *FAILED* [80072F8F] Failed to execute service registration call {7A4EA074-0D0A-4644-AA7B-9F7D5F867323} (cV: W/JwIw/6s0SUg0eJ.1.0.1)
2021/07/30 08:15:15.5481966 32308 46196 IdleTimer WU operation (SR.Windows Defender ID 25, operation # 240) stopped; does use network; is not at background priority
2021/07/30 08:15:15.5491565 43168 6696 ComApi * END * Federated Search failed to process service registration, hr=0x80072F8F (cV = W/JwIw/6s0SUg0eJ.1.0)
Root cause:
No concrete root cause found at this moment.
Fix:
1. Run regedit in admin right.
2. Add the registry DisableRootAutoUpdate type REG_DWORD under the HKLM\Software\Policies\Microsoft\SystemCertificates\AuthRoot. Set the Value of DisableRootAutoUpdate with a data set to 0x1.
3. If the device use proxy for internet and no proxy setting result by running "netsh winhttp show proxy" (run in admin right), go to path HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Connections in registry and set WinHttpSettings (type binary) 1800000000000000010000000000000000000000. Or in simple step, change 28 to 18.
4. Restart computer.
5. Run Windows update again.
Result:
1. If above steps able to fix Windows update issue, wait all updates installed.
2. Finally, remove all fix steps since we do not know the setting is the correct approach for Windows update to have. Normally, removing them not cause any problem later.