STATUS_BAD_IMPERSONATION_LEVEL (0XC00000A5) Fix

What's going on here

You're seeing STATUS_BAD_IMPERSONATION_LEVEL (0XC00000A5) and it's stopping something from working. This typically hits when a program—like a remote desktop client, a VPN service, or a custom Windows service—tries to impersonate a user account with an invalid security level. I've seen this most often with Schannel errors in Event Viewer (source: Schannel, event ID 36888 or 36874) or when using tools like PsExec or OpenVPN.

The actual message is: "A specified impersonation level is invalid." It means the calling process doesn't have the right permission to act as the target user. Don't panic—this is fixable, and you can start with the quickest check.

Simple fix (30 seconds): Check the service account

If this is tied to a Windows service (like a database agent, backup tool, or remote access service), the service might be running under the wrong account. Here's what to do:

1. Press Win + R, type services.msc, hit Enter.
2. Find the service that's failing. Look for the one related to your error—maybe Remote Desktop Services or a third-party tool.
3. Right-click it, choose Properties, go to the Log On tab.
4. If it's set to Local System account, that's usually fine. But if it's using a specific user account (like a domain user), that account might lack the Impersonate a client after authentication privilege.

Quick test: Switch it to Local System account, restart the service, see if the error stops. If it does, you've found the culprit. You can then add the proper privilege to the original user account (more on that below).

Moderate fix (5 minutes): Grant impersonation privileges

If the simple fix didn't work, the underlying issue is often missing user rights. Windows requires a specific privilege to impersonate. Here's how to grant it:

1. Press Win + R, type secpol.msc, hit Enter. (If you're on Windows Home, you'll need to use ntrights or a local group policy editor alternative.)
2. Go to Local Policies → User Rights Assignment.
3. Find Impersonate a client after authentication in the list.
4. Double-click it, click Add User or Group, and type the account that's running the service (e.g., NT SERVICE\YourServiceName or the specific domain user).
5. Click OK, close the policy editor, then reboot or run gpupdate /force in an admin command prompt.

I've seen this fix everything from failing VPN connections to broken remote desktop sessions. If the error persists or you can't access secpol.msc, move to the advanced section.

Advanced fix (15+ minutes): Registry tweak or context check

Sometimes the impersonation level is set too low in the registry, especially for system-wide services. This tripped me up the first time I saw it on a Windows Server 2019 box running a custom RPC service.

Step 1: Check the registry for the impersonation level

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\ImpersonationPrivilege

Navigate there in Regedit (as administrator). If the key doesn't exist, create it as a DWORD (32-bit) value. Set it to 1 to allow delegation (2 is the default for impersonation; 3 is anonymous). I recommend 1 for most services that need to act as the user across remote connections.

Step 2: Verify the calling process's token

Use Process Explorer (from Sysinternals) to check the process that's throwing the error. Find the process, double-click, go to the Security tab, and look at the Impersonation level field. If it says Anonymous or Identification, that's likely the problem. The service needs Impersonation or Delegation to pass credentials properly.

Step 3: Force the service to use a higher level

If you control the source code or the configuration of the service, set the impersonation level to SECURITY_IMPERSONATION (value 2) or SECURITY_DELEGATION (value 3) in the call to CoSetProxyBlanket or ImpersonateNamedPipeClient. For a third-party service, check its documentation for a setting like ImpersonationLevel=2 in its config file.

Step 4: Reboot and test

After any registry change or policy update, restart the service and the machine if needed. The error often disappears after a clean boot.

Final thought

The 0xC00000A5 error is frustrating, but it's almost never a hardware issue—it's permission and context. Start with the service account check, move to user rights, then dig into registry tweaks. You'll be back up in no time.