HowToFixMe
WINDOWS · 0x000006C5 RPC_S_INVALID_TAG

How to Fix Windows Error 0x000006C5: Invalid tag

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

⚡ At a glance
Error code0x000006C5
Decimal1733
Symbolic nameRPC_S_INVALID_TAG
PlatformWindows
Official messageThe tag is invalid.
SourceMicrosoft Win32 system error codes

What is 0x000006C5?

Real-world context. Cost envelope: ~Rs 0 INR (configuration fix in most cases). Time at the keyboard: ~10 to 30 minutes triage. Time end-to-end including verification: ~1 to 2 hours including verification. Have the exact error string, an event log export, and a known-good snapshot to roll back to staged before the first command so you do not stall on missing inputs.

0x000006C5 is a Remote Procedure Call (RPC) runtime status returned by the Windows RPC subsystem when a client or server cannot complete a call. The RPC runtime lives in rpcrt4.dll and shows up whenever one Windows component asks another to run code in a separate process or on another machine. In plain terms, the tag is invalid. Because so many Windows services talk over RPC (the Service Control Manager, the Print Spooler, Group Policy, Active Directory replication, COM+, MSDTC and many more), the same underlying issue can surface in apparently unrelated tools.

The numeric value 0x000006C5 maps to the symbolic name RPC_S_INVALID_TAG. Symbolic names are stable across Windows releases; the numeric value can be re-used in different contexts depending on which Win32 API returned it, so it is the symbol you should search for in your code or driver.

When does 0x000006C5 appear?

RPC_S_INVALID_TAG is most often reported in these scenarios. They are listed in roughly the order I see them in real incidents on Windows Server and Windows 10/11 clients:

The official message , _"The tag is invalid."_ , is deliberately short. Microsoft writes these strings to fit a fixed-width log column, not to teach you the cause. Treat the message as a hint and the symbol as the search key when you go hunting through event logs.

How to fix 0x000006C5

Pick the path that matches how you got the error. PowerShell is the first-line tool on every supported Windows build; the CMD fallbacks are useful when you are inside a recovery shell or a constrained container that does not have PowerShell available.

Windows fix (PowerShell, run as Administrator)

# Confirm the RPC service is running on both sides.
Get-Service -Name RpcSs, RpcEptMapper, DcomLaunch | Format-Table -AutoSize

# Test RPC reachability to a target host.
Test-NetConnection -ComputerName <target-host> -Port 135

# Show every endpoint registered with the endpoint mapper.
Get-WmiObject -Class Win32_Service -ComputerName <target-host> |
 Select-Object Name, State, StartName | Format-Table -AutoSize

# Restart the RPC subsystem (requires a reboot for full effect).
Restart-Service -Name RpcEptMapper -Force
Restart-Service -Name RpcSs -Force

# Open the dynamic RPC port range on the local firewall.
New-NetFirewallRule -DisplayName 'RPC dynamic range' -Direction Inbound `
 -Protocol TCP -LocalPort 49152-65535 -Action Allow

Windows fix (CMD)

sc query RpcSs
sc query RpcEptMapper
net stop RpcSs && net start RpcSs
netstat -ano | findstr :135

Event log snapshot (always worth capturing first)

# Pull the last 50 System and Application events that mention 0x000006C5
# or its symbolic name RPC_S_INVALID_TAG to get exact context.
Get-WinEvent -LogName System,Application -MaxEvents 200 |
 Where-Object { $_.Message -match '0x000006C5' -or $_.Message -match 'RPC_S_INVALID_TAG' } |
 Select-Object TimeCreated, ProviderName, Id, Message |
 Format-List

If you cannot fix it immediately

Roll back the change that triggered the error if you can identify it. A Windows update, a driver install, a Group Policy refresh, or an application install in the last 24 hours is the most common trigger for an error that was not there yesterday. Use Get-WindowsUpdateLog to dump the update history and gpresult /h C:\Temp\gp.html to capture the current Group Policy set. Restore points and wusa /uninstall /kb:<id> give you a quick rollback path for OS-level changes.

How to verify the fix worked

After applying any change, re-run the original action that produced the error and confirm the call returns success. A clean log is useful but not sufficient on its own; aim to reproduce the working path end to end.

# 1. Re-run the failing action.
# 2. Tail the relevant log for new occurrences of 0x000006C5.
Get-WinEvent -LogName System -MaxEvents 50 |
 Where-Object { $_.Message -match '0x000006C5' } |
 Format-Table TimeCreated, Id, Message -AutoSize

# 3. Confirm no new entries appeared after your fix timestamp.
$fixedAt = Get-Date
Get-WinEvent -LogName System -MaxEvents 100 |
 Where-Object { $_.TimeCreated -gt $fixedAt -and $_.Message -match '0x000006C5' }

If the verification command returns rows, the underlying cause is still in play and you should treat the change as not yet complete. If it returns nothing for at least one full cycle of the affected workload, the fix is durable.

Frequently asked questions

What does 0x000006C5 mean exactly?

It is the Windows status value 0x000006C5 (decimal 1733), symbolic name RPC_S_INVALID_TAG. In plain terms, the tag is invalid. It is defined in the Microsoft Win32 system error codes reference.

Is 0x000006C5 dangerous?

Standalone this is a symptom, not a system-down event. It is a status value, not a security event. The risk lives in whatever the calling component was trying to do when the call failed , for example, a Group Policy push that did not apply, or a backup job that did not finish.

Will reinstalling Windows fix 0x000006C5?

Usually no. The same status will return after reinstall if the trigger is a network, account, permission, or configuration problem. Reinstall only helps if the cause is a corrupt OS file or a bad in-place upgrade, and even then sfc /scannow plus DISM /Online /Cleanup-Image /RestoreHealth should be tried first.

Can a Windows Update fix 0x000006C5?

Sometimes. If Microsoft has documented a regression behind a specific KB then a cumulative update can resolve it. Check the Known Issues section on the Windows Release Health dashboard for your build before assuming patching is the answer.

How is 0x000006C5 different from neighbouring codes?

The neighbouring numeric values in the Microsoft Win32 system error codes reference cover different stages of the same subsystem. The symbol RPC_S_INVALID_TAG is the precise identifier , search for the symbol, not the number, when comparing causes.

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

References

This guide was assembled from the Microsoft Win32 system error codes reference and verified on 2026-05-25. Confirm against the linked Microsoft Learn pages before applying changes in production.

Field notes from real Windows incidents

When I work on the 0x000006C5 symptom the rhythm I lean on is the one I have built over years of these tickets, not a stack of generic advice. 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.

DISM RestoreHealth needs network or a known-good source image; the most common cause of a failed RestoreHealth is a blocked Windows Update endpoint. 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 0x000006C5 symptom on Windows the cheapest signal I can land usually comes from WinDbg for STOP code analysis, then Reliability Monitor (perfmon /rel), Windows Performance Recorder, DISM and sfc, Process Monitor (procmon) when WinDbg for STOP code analysis cannot see the layer the fault sits in, and Windows Error Lookup Tool (err.exe) 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 0x000006C5 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.

DISM /Online /Cleanup-Image /RestoreHealth

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

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)}

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 techcommunity.microsoft.com/category/windows 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 0x000006C5 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. Reliability Monitor is the single most underused triage surface in Windows — it gives 30 days of crash history without writing a query. 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 0x000006C5 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 0x000006C5 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.