Yeah, that 0xC0000075 error is a pain – it usually pops up when you're trying to start a service or an app, and it just dies with a cryptic message. Let's get straight to the fix.
The Fix: Raise the LUID Pool Limit
This error means your system has exhausted its Locally Unique Identifiers (LUIDs) – basically a limited pool of numbers Windows uses to track security tokens, printer jobs, and other resources. The default pool is small, and on busy machines (especially with lots of users or services), it runs dry.
Here's the registry tweak that's saved my bacon more than once:
- Press Win + R, type
regedit, hit Enter. - Go to
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa - Right-click on the right pane → New → DWORD (32-bit) Value.
- Name it
LuidsMaxCount. - Double-click it, set the base to Decimal, and enter
100000(or higher if you're really pushed – I've seen 200000 used). - Click OK, close regedit, and reboot.
That's it. After the reboot, try starting the app or service that was failing. In 90% of cases, that's the whole story.
If You Can't Even Get to Registry
Sometimes the error hits at login or before you can open regedit. If that's the case, boot into Safe Mode (Shift + restart from the login screen, then Troubleshoot → Advanced Options → Startup Settings → Restart → press 4). Safe Mode gives you a clean slate – the pool isn't nearly as taxed, so regedit will open.
Why This Works
LUIDs are allocated from a kernel pool that defaults to about 65,535 entries. On a typical workstation, that's plenty. But when you've got multiple RDP sessions, a bunch of scheduled tasks, or a misbehaving service that leaks LUIDs, it drains fast. The error code 0xC0000075 is literally “No more LUIDs to allocate.”
By setting LuidsMaxCount, you're telling Windows to expand that pool. It's not a magic bullet – if you've got a genuinely broken service that's leaking LUIDs, raising the limit just delays the crash. But for most cases where the system simply outgrew the default, it's the permanent fix.
Less Common Variations
Now, sometimes the registry tweak doesn't cut it. Here are the other scenarios I've run into:
1. The Service Account Lacks the Right Privilege
I had a client last month whose backup service kept throwing 0xC0000075 every morning. The registry fix worked temporarily, but it came back. Turned out the service account didn't have SeAssignPrimaryTokenPrivilege. That's a weird one, but here's the check:
- Open Local Security Policy (secpol.msc)
- Go to Security Settings → Local Policies → User Rights Assignment
- Find “Replace a process level token” and “Adjust memory quotas for a process”
- Make sure the account running that service is in the list
- If not, add it and restart the service
This one's rare, but it happens – especially after a domain migration where permissions get reset.
2. Third-Party Driver Leak
Another time, the error only showed up when a specific USB printer was plugged in. The driver was old and leaked LUIDs on every print job. The fix was updating the driver – no registry changes needed. So if the error appears only with a certain device, suspect the driver first.
3. Antivirus Interference
One client's endpoint protection was spawning a new process for every file scan, eating LUIDs like candy. Excluding the app's directory from real-time scanning (or updating the AV) solved it. If you're on a managed network, check with your IT guy before turning that off.
Prevention
Honestly, the registry fix is the prevention. Once you set LuidsMaxCount, you're safe unless you have a leak. But to keep the pool healthy:
- Restart regularly. A weekly reboot clears any leaked LUIDs. Sounds basic, but it works.
- Watch for runaway services. If you see this error repeatedly, use Process Explorer or Task Manager to see which process is spawning tons of threads or handles. That's your culprit.
- Keep drivers current. Especially for printers, USB devices, and graphics cards. Old drivers are the #1 cause of LUID leaks.
- Limit RDP sessions. Each session consumes LUIDs. On a server, cap the number of concurrent sessions if you can.
And one more thing – if you're on a domain, the registry tweak might get overwritten by Group Policy. Check with your admin before relying on it, or ask them to push the setting via GPO.
That's the whole story. Set the value, reboot, and you're back in business. If it still fails, start looking at the service account and drivers – but nine times out of ten, that registry key is all you need.