Fix 0X0000099A NERR_PasswordMismatch on Windows Server

Quick Answer

Open Command Prompt as admin, type net use * /delete, then reconnect to the share using net use Z: \\ServerName\ShareName /user:DomainName\Username * — enter the correct password when prompted.

Why This Happens

The 0X0000099A error — also called NERR_PasswordMismatch — shows up when Windows tries to connect to a network share or printer and the password stored on your machine doesn't match what the server expects. This usually happens after you change your domain password or if cached credentials get corrupted. I've seen it most often on Windows 10 machines connecting to a Windows Server 2019 file server after a forced password reset. The error message is short: "A password mismatch has been detected." It's frustrating because Windows keeps using old credentials even after you've typed the new one.

Fix Steps

1. Open Command Prompt as Administrator. Press the Windows key, type cmd, right-click Command Prompt, and select "Run as administrator." If you don't do this, some commands won't work.
2. Clear all saved network connections. Type net use * /delete and press Enter. You should see something like "You have these remote connections:" followed by a list of drives. Type Y for each one. If you get "There are no entries in the list," that's fine — move on.
3. Open Credential Manager. Press Windows key, type credential manager, and open it. Click Windows Credentials. Look for any entries under "Generic Credentials" that mention the server name or IP you're trying to connect to. Click the arrow next to each one, then click Remove. Confirm the deletion.
4. Reconnect to the share. In the same Command Prompt window, type net use Z: \\ServerName\ShareName /user:DomainName\Username *. Replace Z: with the drive letter you want, ServerName with the actual server name, ShareName with the share name, and DomainName\Username with your domain credentials. For example: net use Z: \\fileserver\docs /user:CONTOSO\jsmith *. Press Enter. You'll be prompted for the password. Type it carefully — Windows won't show the characters. Press Enter again.
5. Verify the connection. If the command returns "The command completed successfully," you're good. Open File Explorer and check that Z: drive shows up. If you get error 0X0000099A again, don't skip to the alternative fixes — repeat step 3 and remove ALL credentials related to that server, even ones you think are old.

Alternative Fixes If the Main One Fails

Reset the machine password

Sometimes the computer's own password is out of sync with the domain. Open Command Prompt as admin and type Reset-ComputerMachinePassword -Server DomainControllerName -Credential DomainName\AdminAccount. Replace DomainControllerName with an actual DC name (like DC01) and provide admin credentials. This forces a password reset with the domain. Reboot, then try connecting again.

Check for time sync issues

If the time on your machine is off by more than 5 minutes from the domain controller, Kerberos authentication breaks. Open Command Prompt as admin and type w32tm /resync. If it fails, check with w32tm /query /status. You can also set it manually: net time \\DomainControllerName /set.

Disable IPv6 temporarily

I've seen IPv6 cause weird credential issues on some networks. Open Network Connections (ncpa.cpl), right-click your active network adapter, select Properties, uncheck "Internet Protocol Version 6 (TCP/IPv6)", click OK, then restart. This is a test — if it works, leave it off or troubleshoot your IPv6 configuration.

Prevention Tip

After changing your domain password, always run net use * /delete before connecting to any network shares. Better yet, sign out and sign back in to Windows. That clears credential cache entirely. Also, never check "Remember my credentials" when connecting to a share on a machine that's not yours — that stores the password permanently and causes this exact error when the password changes.