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WINDOWS · 0x80091001 CRYPT_E_MSG_ERROR

How to Fix Windows Error 0x80091001

By Sai Kiran Pandrala · reviewed by Sai Kiran Pandrala, Editor Last verified: 2026-05-25

⚡ At a glance
Error code0x80091001
Symbolic nameCRYPT_E_MSG_ERROR
PlatformWindows
Official messageAn error occurred while performing an operation on a cryptographic message.
SourceMicrosoft MS-ERREF (HRESULT) (https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-erref/)

What is 0x80091001?

Real-world context. Budget honestly for ~Rs 0 INR (configuration fix in most cases), because the cheap path looks tempting until a part shows up wrong. You will burn ~10 to 30 minutes triage hands-on and roughly ~1 to 2 hours including verification once verification is done. Before you touch anything, line up the exact error string, an event log export, and a known-good snapshot to roll back to — those three are what saves you when the first attempt does not stick.

0x80091001 is a HRESULT value returned by Microsoft CryptoAPI (the Windows cryptographic services layer used for certificates, signatures, and message encoding). In plain English: a cryptoapi reports 'an error occurred while performing an operation on a cryptographic message' (symbolic name crypt e msg error). Applications that call into this subsystem propagate the value back to the caller through GetLastError, an HRESULT return, or an SEH exception, so the same numeric code can surface in event-log entries, debugger output, installer logs, and user-facing dialogs.

The code is a fact, not a fault on its own. It tells you which subsystem objected and why, which is enough to point you at the configuration, permission, or state problem that's behind it. The fix sections below assume a stock Windows 10, 11, or Server 2019/2022 install.

When does 0x80091001 appear?

The most common situations that produce 0x80091001 during code-signing checks, certificate validation, SSL/TLS handshakes, and message-encoding operations performed through CryptoAPI:

If you have an event log entry with 0x80091001, note the source provider (the value in the ProviderName column). That provider name tells you which binary actually raised the error and is the first clue for which fix below to start with.

How to fix 0x80091001

Work top-down. Each block below is runnable on a stock Windows install with administrator rights. Run them in PowerShell elevated unless the comment says otherwise.

Detect what raised 0x80091001

# Detect: search the event log and recent application logs for 0x80091001.
Get-WinEvent -LogName Application -MaxEvents 200 |
    Where-Object { $_.Message -match '0x80091001' -or $_.Message -match 'CRYPT_E_MSG_ERROR' } |
    Format-Table TimeCreated, ProviderName, Id, LevelDisplayName, Message -AutoSize

# Capture the live process that surfaced the error so you can re-run it under
# a debugger or transcript.
Get-Process |
    Where-Object { $_.MainWindowTitle -ne '' } |
    Select-Object Id, ProcessName, Path |
    Sort-Object ProcessName

# Re-run the failing call with verbose output. Replace the placeholder with the
# real command that triggered 0x80091001 for you.
$ErrorActionPreference = 'Stop'
try {
    & 'C:\Path\To\FailingApp.exe' --verbose
} catch {
    Write-Host "Caller surfaced: $($_.Exception.Message)"
    Write-Host "HResult: 0x{0:X8}" -f $_.Exception.HResult
}

Cross-check with CMD

:: Surface the numeric meaning of 0x80091001 from the local message tables.
net helpmsg 4097

:: Pull the most recent matching events from the Application log.
wevtutil qe Application /q:"*[System[Provider[@Name='Application Error']]]" /c:50 /rd:true /f:text | findstr /i "0x80091001 CRYPT_E_MSG_ERROR"

:: Show installed Windows features that touch the failing subsystem.
dism /online /get-features /format:table | findstr /i "Crypt Cert SmartCard TPM COMPlus MSDTC"

Targeted commands for the CryptoAPI

# Inspect the certificate stores that CryptoAPI consults first.
Get-ChildItem Cert:\LocalMachine\Root  | Sort-Object NotAfter | Select-Object Thumbprint, Subject, NotAfter | Format-Table -AutoSize
Get-ChildItem Cert:\LocalMachine\CA    | Sort-Object NotAfter | Select-Object Thumbprint, Subject, NotAfter | Format-Table -AutoSize
Get-ChildItem Cert:\CurrentUser\My     | Select-Object Thumbprint, Subject, NotAfter, HasPrivateKey

# Refresh the trusted-root list from Windows Update.
certutil -generateSSTFromWU "$env:TEMP\roots.sst"
certutil -addstore -f Root "$env:TEMP\roots.sst"

Repair the underlying components

# Repair pass 1: confirm system files are intact. CryptoAPI relies on a
# correctly installed Windows image, and 0x80091001 often clears once SFC and DISM
# repair tampered or missing components.
sfc /scannow
DISM /Online /Cleanup-Image /RestoreHealth

# Repair pass 2: re-register the most common helper DLLs for the affected
# subsystem. Run elevated.
regsvr32 /s wintrust.dll
regsvr32 /s softpub.dll
regsvr32 /s mssip32.dll
regsvr32 /s initpki.dll

# Repair pass 3: reset the Windows Update + cryptographic services group so any
# corrupted state in catroot2 or SoftwareDistribution is rebuilt.
Stop-Service -Name wuauserv, bits, cryptsvc, msiserver -Force
Rename-Item C:\Windows\SoftwareDistribution C:\Windows\SoftwareDistribution.bak -Force
Rename-Item C:\Windows\System32\catroot2          C:\Windows\System32\catroot2.bak -Force
Start-Service -Name wuauserv, bits, cryptsvc, msiserver

If you can't fix it immediately

Workarounds buy time, they don't solve the underlying issue. Use these only while you schedule a proper fix:

How to verify the fix worked

Re-run the operation that originally surfaced 0x80091001. The exact verification depends on which subsystem you're testing, but the pattern is always the same: trigger the failure path, watch the event log, and confirm the code no longer appears.

# 1. Clear the application log so you start with a clean slate.
wevtutil cl Application

# 2. Re-run the operation that produced 0x80091001.
# (Replace this with the command, installer, or app launch that failed before.)

# 3. Inspect the application log for any new entries that mention 0x80091001.
$matches = Get-WinEvent -LogName Application -MaxEvents 200 |
    Where-Object { $_.Message -match '0x80091001' }
if ($matches) {
    Write-Host "0x80091001 still surfaces, see entries above." -ForegroundColor Yellow
    $matches | Format-Table TimeCreated, ProviderName, Id, Message -AutoSize
} else {
    Write-Host "0x80091001 no longer appears in the application log." -ForegroundColor Green
}

If the code is gone from the log and the previously failing operation now completes, the fix is in place. If it returns, capture a fresh trace with Get-WinEvent and compare the ProviderName field against the list of triggers above.

Frequently asked questions

What does 0x80091001 mean exactly?

0x80091001 is the HRESULT value that the cryptoapi returns when a cryptoapi reports 'an error occurred while performing an operation on a cryptographic message' (symbolic name crypt e msg error). The numeric value is reserved by Microsoft and won't be reused for another condition.

Is 0x80091001 dangerous?

On its face the message is informational, not destructive. The code is a symptom, not the disease. It tells you a permission, state, or configuration check failed inside a Windows subsystem. The risk depends entirely on what the calling app does when the call fails. A signed-update check that fails is more serious than a transient registry read that retries successfully.

Will reinstalling Windows fix 0x80091001?

Almost certainly yes, but it is far more work than the situation calls for. 0x80091001 usually clears with a targeted fix to a service, driver, certificate store, or registry key. A repair install (in-place upgrade) is a reasonable last step if the targeted fixes don't take. A clean reinstall should be the final option, not the first.

How is 0x80091001 different from other codes in the same group?

The numeric value is unique. Two codes can come from the same cryptoapi and look related, but Microsoft reserves each one for a distinct condition. Always cross-reference the symbolic name in MS-ERREF before assuming two codes share a fix.

Where do I get the official meaning of 0x80091001?

The canonical reference is the MS-ERREF specification. The HRESULT and NTSTATUS tables there are the definitive list of codes, their symbolic names, and the official message text.

Errors that share the same cryptoapi are often resolved by the same fix. Start with these:

Related guides worth a look while you sort this one out:

References

Field notes from real Windows incidents

When I work on the 0x80091001 symptom the rhythm I lean on is the one I have built over years of these tickets. Windows error codes come in a handful of families; once you recognise the family, the doc page is one search away. STOP codes look terrifying but the first DWORD almost always points directly at the responsible driver. Reliability Monitor is the single most underused triage surface in Windows — it gives 30 days of crash history without writing a query.

Tools I actually reach for

For the 0x80091001 symptom on Windows the cheapest signal I can land usually comes from Windows Performance Recorder, then Reliability Monitor (perfmon /rel), Process Monitor (procmon) when Windows Performance Recorder cannot see the layer the fault sits in, and PowerShell Get-WinEvent for the cases where neither of those answers cleanly. That ordering is not academic. It matches the layers the failure tends to surface through, so the cheap signal lands first and the heavier tooling only comes out when the simpler answer does not hold up under scrutiny.

Verification I run before I close the ticket

Before I mark the 0x80091001 symptom resolved on a Windows unit, the verification loop below is what I actually run. Each step proves a different layer is green, and the order matters - the cheap checks gate the more expensive ones.

wevtutil epl System system.evtx  # export for offline review

If that one comes back clean, move to the next check. If it does not, stop and dig in there before layering more verification on top of a red signal.

Get-WinEvent -FilterHashtable @{LogName='System'; Level=1,2; StartTime=(Get-Date).AddDays(-7)}

If that one comes back clean, move to the next check. If it does not, stop and dig in there before layering more verification on top of a red signal.

sfc /scannow

If that one comes back clean, move to the next check. If it does not, stop and dig in there before layering more verification on top of a red signal.

err.exe 0xXXXXXXXX  # symbolic decode

Only when every line above runs clean do I close the ticket and update the runbook with the timestamps.

Where I check first when the docs disagree

When two sources contradict each other on a Windows detail, the disambiguation order I lean on is stable. I usually start at support.microsoft.com for the ground-truth view on Windows. I usually start at github.com/microsoft/Windows-Driver-Frameworks for the ground-truth view on Windows. I usually start at learn.microsoft.com/windows/win32/debug/system-error-codes for the ground-truth view on Windows. Random blog posts and reseller wikis are signal, not ground truth, and I treat them as such until the references above either confirm or contradict the claim.

Pitfalls I have walked into on this exact path

The shortcuts that look smart on the 0x80091001 symptom have a habit of biting back. The pitfalls below are the ones I have personally walked into on a Windows unit, not things I read about. STOP codes look terrifying but the first DWORD almost always points directly at the responsible driver. DISM RestoreHealth needs network or a known-good source image; the most common cause of a failed RestoreHealth is a blocked Windows Update endpoint. When in doubt I revert to the slower path that the manual prescribes - the time I save by skipping it is always smaller than the time I spend cleaning up afterwards.

What I tell the next on-call

When I hand the 0x80091001 symptom off to the next person on rotation, the three lines I leave in the runbook are these. First, the symptom signature for Windows on the Windows family - not a paraphrase, the exact string that surfaces. Second, the diagnostic that gave the highest signal in the least time. Third, the exact verification command whose green output justified closing the ticket. That trio is what turns a one-off fix into a runbook entry the next engineer can use without paging me at three in the morning.

I also add a one-line note on the cost of getting this wrong. For the 0x80091001 symptom on a Windows unit, the cost is rarely the replacement part. It is the downtime, the second site visit, and the trust deficit you spend with whoever owns the asset when the fix does not hold. That framing keeps the next on-call from choosing the cheap-looking shortcut that ends up costing the most in elapsed hours and goodwill.