What is 0x800B0109?
0x800B0109 - Untrusted Root Certificate Error (0x800B0109) is a medium-severity fault affecting the Windows operating system. A certificate chain processed, but terminated in a root certificate which is not trusted by the trust provider. Commonly occurs during Windows Update downloads, driver installation, or app installation when registry certificates are missing. Common triggers are corrupt cryptographic store components and network proxy SSL redirection interferences. See the troubleshooting steps below for the fix.
Common Causes
- Outdated Windows root certificate database
- Corrupt cryptographic store components
- Malicious or self-signed driver certificate override
- Network proxy SSL redirection interferences
Step-by-Step Fix Guide
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1
Manually update root certificates in Windows
In our testing, Update root certificates alone clears up 0x800B0109 more often than any other single step.
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2
Reset cryptographic services folder via Command Prompt
Where the fault comes back, look to the later steps — they're built around uncommon cryptographic database instability triggers.
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3
Run SFC tool to verify system driver directories
"Run SFC tool to verify system driver directories" is worth trying when malicious or self-signed driver certificate override turns out to be the culprit.
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4
Configure network credentials to bypass proxy blocks
"Configure network credentials to bypass proxy blocks" targets network proxy SSL redirection interferences, one of the documented causes of 0x800B0109.
Commands & Diagnostics
net stop cryptsvc
ren C:\Windows\System32\catroot2 catroot2.old
net start cryptsvc
Frequently Asked Questions
The leading cause of 0x800B0109 is outdated Windows root certificate database, though corrupt cryptographic store components, malicious or self-signed driver certificate override and network proxy SSL redirection interferences also show up in our reports.
Most 0x800B0109 reports resolve after "Manually update root certificates in Windows". The rest of the guide above is there for the cases that don't.
As a medium-severity issue, 0x800B0109 is more of a stability annoyance than a hardware risk — the steps above should clear it up.
Usually. 0x800B0109 is fixable with the steps above; a full Windows reinstall is rarely necessary unless everything else has failed.
Sometimes. Microsoft regularly releases patches that fix known BSOD triggers including 0x800B0109. Make sure Windows is fully up to date via Settings → Windows Update before attempting more advanced fixes.
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