When you install or reinstall a Windows Server operating system on a Contabo server, an initial password for administrative access (Administrator account) is provided.

If you have lost or forgotten the Administrator password, you can reset it by booting the server into Rescue Mode and manually clearing the password.

The steps below explain how to reset the local Windows Administrator password on a Contabo server using Rescue Mode. 

Step 1: Activate rescue system

Before the Administrator password can be reset, the server must be started in Rescue System. 

1. Log in to the Contabo Customer Panel

2. Select the affected server from the Servers & Hosting drop-down menu

3. Activate the Rescue System

4. Reboot the server

Once Rescue System is active, you will receive temporary login credentials for SSH access. 

Note: Rescue System runs a Linux-based environment that allows access to the Windows disk. 

Step 2: Connect to the Server and Mount the Windows Partition 

Connect to the server

Connect to your server using SSH with the Rescue Mode credentials.

Alternatively, you may use the VNC / KVM console from the Customer Control Panel.

Identify and mount the Windows partition

In most cases, the Windows system partition is /dev/sda2.
First, repair and mount the partition: 

ntfsfix /dev/sda2
mount -t ntfs-3g /dev/sda2 /mnt

If mounting fails, verify the correct partition using:

lsblk

Step 3: Clear the Administrator Password 

The Windows user database is stored in the SAM file. This file can be edited using the chntpw tool. 

List Windows user accounts 

chntpw -l /mnt/Windows/System32/config/SAM 

Example output:

| RID -|---------- Username ------------| Admin? |- Lock? --|  

| 01f4 | cloudbase-admin               | ADMIN | dis/lock |  

| 03e8 | cloudbase-init                | ADMIN |         |  

| 01f7 | DefaultAccount                |       | dis/lock |  

| 01f5 | Guest                         |       | dis/lock |  

| 01f8 | WDAGUtilityAccount            |       | dis/lock | 

In most cases, Administrator is the correct account. 

Reset the password

Run the following command: 

chntpw -u Administrator /mnt/Windows/System32/config/SAM

If the account name Administrator does not exist, try: 

chntpw -u admin /mnt/Windows/System32/config/SAM

Or:

chntpw -u cloudbase-admin /mnt/Windows/System32/config/SAM

Clear the password

When the User Edit Menu appears: 

1. Type 1 → Clear (blank) user password 

2. Press Enter

If the account is disabled, use option 2 first to unlock it.

Then:

• Type q to quit
• Confirm saving changes by typing y

You should see confirmation that the SAM file was written successfully. 

Step 4: Reboot the server normally

Exit Rescue System and reboot the server back into normal operation.

The Administrator account now has no password set. 

⚠️Security warning:
While the Windows instance is running without an Administrator password, even for a short period of time, and is publicly accessible from the Internet, it may be vulnerable to unauthorized access.
For this reason, a new Administrator password must be set immediately after the reset process is completed.

Establish a connection via VNC and enter a new, simple password directly in the form. This password will be set for the administrator account. (The VNC keyboard layout is different in most cases. Therefore, create a simple password and then change it to a more complex one via RDP.) 

Step 5: Set a New Administrator Password (Mandatory) 

Set a new password 

1. Connect to the server via RDP

2. Open Command Prompt as Administrator

3. Run:

net user Administrator *

4. Enter and confirm a strong password 

You can now log in normally using the new Administrator password.

For detailed guidelines, see How to Change the Windows Administrator Password.

Additional notes:

• This procedure resets the local Administrator account only
• Domain accounts are not affected
• BitLocker-encrypted disks must be decrypted before this method can be used
• Contabo Support cannot retrieve or view your passwords.