SEC_E_NOT_OWNER (0x80090306) fix for small business PCs

What causes SEC_E_NOT_OWNER (0x80090306)?

This error pops up when Windows gets confused about who owns the current logon session. You'll see it most often when you try to access network shares, mapped drives, or remote desktops after switching users. I had a client last month whose whole print queue died because of this — the print server wouldn't accept their credentials after they switched accounts.

The error code 0x80090306 translates to "the caller is not the owner of the desired credentials." That's Microsoft's fancy way of saying "your session is messed up."

Cause #1: Fast User Switching gone wrong

This is the most common trigger. You log in as user A, then switch to user B without fully logging out. When user B tries to access something that still has user A's credentials cached — boom, error 0x80090306.

The fix

1. Log out completely. Don't just switch users — click Start > your profile icon > Sign out.
2. Wait 10 seconds. I know it feels like forever, but the credential cache needs to clear.
3. Log back in as the user who needs access.

That fixes it 80% of the time. If it doesn't, move to the next step.

I've seen this exact scenario with a client who had a shared computer at a dental office. Receptionist would switch users to let the dentist check records, then get this error trying to access the X-ray database. Full sign-out fixed it every time.

Cause #2: Stale credentials in the Credential Manager

Sometimes Windows holds onto old credentials even after you log out. This is especially common with RDP connections or mapped drives that use saved passwords.

The fix

1. Open Control Panel. Search for "Credential Manager."
2. Click on Windows Credentials.
3. Look for any entries that match the server or share you're trying to access. They'll have names like TERMSRV/servername or MicrosoftAccount:user@domain.com.
4. Remove those entries. Right-click and select Remove.
5. Close Credential Manager and try your access again.

One time I had a client who couldn't access their QuickBooks company file on a network drive. This error popped up every morning. Turned out they had three old RDP credentials saved from a previous IT guy. Removing those fixed it instantly.

Cause #3: Corrupted Windows logon session

If logging out and clearing credentials doesn't work, the actual logon session token might be corrupted. This happens more often on domain-joined computers, but I've seen it on workgroup machines too.

The fix

1. Press Ctrl + Shift + Esc to open Task Manager.
2. Go to the Users tab. You'll see all active sessions.
3. Right-click on any session that doesn't belong to you and select Sign off.
4. Still broken? Restart the Credential Manager service:

net stop CredentialManager && net start CredentialManager

Run that in an elevated Command Prompt (right-click > Run as administrator).

If that doesn't work, you might need to restart the Local Security Authority service. But be careful — this can knock out other services. Only do this if you're comfortable with a reboot afterward.

net stop SamSs && net start SamSs

Had a client last week whose computer kept throwing 0x80090306 every 30 minutes. Turned out a background service (something from their old VPN client) was holding onto a stale session. Restarting the Local Security Authority service cleared it right up.

Quick-reference summary table

Most of the time, this error is just Windows being Windows with user switching. The full sign-out fix works for 8 out of 10 cases. If you still get the error after trying all three fixes, you might have a deeper issue like a corrupted user profile — but that's rare. Start with the simple stuff.