Windows Server 2025 Datacenter + 100 Users — Comprehensive Installation, Activation, and Licensing Guide

Before You Begin

Windows Server 2025 Datacenter is the latest and most advanced edition of Microsoft's server operating system, designed for highly virtualized environments and software-based data centers. The Datacenter edition provides unlimited rights to run virtual machines on a single server after meeting the licensing requirements for physical cores. In the package offered by KluczeSoft.pl, you receive a Windows Server 2025 Datacenter license along with 100 User CAL (Client Access License) access licenses, allowing for legal access to the server for 100 users.

Purchasing from KluczeSoft.pl means:

• Savings — the price of 6490 zł for the complete package (Windows Server 2025 Datacenter + 100 User CALs) is significantly less than buying them separately.
• Legality — original product key, VAT invoice, technical support.
• Security — guarantee of authenticity and the possibility of return.

Important: Licensing Windows Server 2025 Datacenter requires both a license for the server's physical cores and the appropriate number of CALs for users or devices. CALs are version-specific — Windows Server 2025 requires 2025 CALs.

Technical Support and Product Lifecycle

KluczeSoft.pl provides support for activation and installation throughout the entire period of Microsoft's mainstream support.

System Requirements

To properly install and run Windows Server 2025 Datacenter, your server must meet the following hardware and software requirements (based on Microsoft documentation):

Note: When installing on a virtual machine, it is recommended to allocate at least 2 cores and 4 GB of RAM per instance.

For any questions or concerns, please contact us at [email protected] or call 00 800 121 1654.

Step 1: Preparing for Installation

1. Download the ISO image of Windows Server 2025 Datacenter from the official Microsoft website or from the link provided by KluczeSoft.pl.
2. Verify the SHA256 checksum of the downloaded ISO file to ensure it has not been damaged.
3. Prepare the installation media — burn the ISO image to a USB drive (at least 8 GB) using Rufus or the Windows USB/DVD Download Tool.
4. Back up all important data on the server if you are installing the system on existing hardware.
5. Ensure you have the product key (received from KluczeSoft.pl) and a list of users to whom you will assign CALs.

Step 2: Installing Windows Server 2025 Datacenter — Step by Step

1. Starting the Installer

• Connect the prepared USB drive or insert the DVD into the server.
• Enter the BIOS/UEFI and set the boot device to USB/DVD.
• Save the changes and restart the server.

2. Installer Welcome Screen

• Select the installation language (Polish), time format, and keyboard layout.
• Click Next.

3. Starting the Installation

• Click Install Now.

4. Selecting the System Edition

• From the list, select Windows Server 2025 Datacenter (Desktop Experience) or Windows Server 2025 Datacenter (Server Core) — we recommend Desktop Experience for beginners.
• Click Next.

5. Accepting the License Terms

• Read and accept the license terms.
• Check the box I accept the license terms and click Next.

6. Choosing the Installation Type

• Select Custom: Install only Windows (Advanced).

7. Selecting the Partition

• Specify the disk/partition for the system installation.
• If this is a new server, create a new partition and format it.
• Click Next.

8. Installing System Files

• The installer will copy files and install the system. This may take several to several dozen minutes.
• After completion, the server will restart.

9. Initial Configuration

• Set the password for the Administrator account.
• Log in to the system after the first boot.

Step 3: Activating with the Product Key

Activation is required to use the full functionality of the system and maintain the legality of use. You can do this in two ways: through the graphical interface or the command line.

Method 1: Activation through the Graphical Interface (GUI)

1. Open Settings > Update and Security > Activation.
2. Click Change product key.
3. Enter the product key received from KluczeSoft.pl (e.g., XXXXX-XXXXX-XXXXX-XXXXX-XXXXX).
4. Click Next, then Activate.

Method 2: Activation through the Command Line

1. Open Command Prompt as Administrator:
   • Right-click on the Start menu > Windows Terminal (Administrator) or Command Prompt (Administrator).
2. Type the command:

   C:\Windows\System32\slmgr.vbs /ipk XXXXX-XXXXX-XXXXX-XXXXX-XXXXX
   

   (Replace XXXXX... with your product key)
3. Then activate the system with the command:

   C:\Windows\System32\slmgr.vbs /ato
   

Activating CALs (User CALs)

Access licenses (CALs) are documented and assigned in the organization's licensing documentation. They do not require activation in the system but must be available upon request for an audit.

If you need assistance, please contact us at [email protected] or call 00 800 121 1654.

Step 4: Activation Verification

After activating the system, you can check its status:

1. Open the Command Prompt as an Administrator.
2. Enter the command:

   C:\Windows\System32\slmgr.vbs /xpr
   

   You will see a message about the activation status (e.g., "The system is permanently activated").

Additionally, you can check the license details:

C:\Windows\System32\slmgr.vbs /dli

or

C:\Windows\System32\slmgr.vbs /dlv

Step 5: Post-Installation Configuration

After the first launch and activation, we recommend performing the following actions:

1. Install the latest updates — go to Settings > Update & Security > Windows Update and download all available fixes.
2. Configure the network — set a static IP address, mask, gateway, and DNS in Control Panel > Network and Sharing Center > Change adapter settings.
3. Change the server name — in System > About > Rename this computer.
4. Add the server to the domain (if necessary) — Control Panel > System > Advanced system settings > Computer Name > Change.
5. Install roles and features — open Server Manager > Manage > Add Roles and Features (e.g., Active Directory, Hyper-V, File Server).
6. Configure the firewall and security — adjust the settings in Windows Defender Firewall.
7. Create user accounts — in Server Manager > Tools > Active Directory Users and Computers (if AD is configured).

Step 6: Troubleshooting

Below, you will find the most common errors and their solutions:

1. Error: "The product key is invalid"

• Solution: Make sure you enter the key without spaces and special characters. Check if you are using the key for the Datacenter 2025 edition, not Standard or another version. If the problem persists, contact KluczeSoft.pl.

2. Error: "Cannot connect to the Microsoft activation server"

• Solution: Check the server's internet connection. Ensure that the firewall is not blocking ports 80/443. Try activating the system again after a few minutes.

3. Error: "Windows cannot be installed on this disk"

• Solution: Ensure that the disk is set as GPT (for UEFI) or MBR (for BIOS). You can format the disk during installation or use the Diskpart tool:

  diskpart
  list disk
  select disk X
  clean
  convert gpt
  exit
  

4. Error: "No network drivers after installation"

• Solution: Download the latest network drivers from the server manufacturer's website and install them manually through Device Manager.

5. Error: "Activation failed — 0xC004F074"

• Solution: This code indicates a problem with communication with the KMS server. If you are using a MAK key, ensure that you are not trying to activate through KMS. If necessary, use the command:

  C:\Windows\System32\slmgr.vbs /ipk XXXXX-XXXXX-XXXXX-XXXXX-XXXXX
  C:\Windows\System32\slmgr.vbs /ato
  

6. Error: "No permissions to install roles/functions"

• Solution: Ensure that you are logged in as an Administrator. If the server is in a domain, check the account permissions.

7. Error: "CALs are not visible in the system"

• Solution: CALs are documented outside the operating system. Store the license documentation and user assignments for audit purposes.

For further assistance, please contact us at [email protected] or call 00 800 121 1654.

Step 7: Comparing versions and prices at KluczeSoft.pl

You save over 2000 zł by purchasing the Datacenter + 100 User CALs package at KluczeSoft.pl compared to buying them separately.

You can find more details on the product page: /windows-server-2025

Summary

Windows Server 2025 Datacenter with a 100 User CALs package is the ideal solution for large companies and data centres that require high performance, scalability, and licensing flexibility. With this guide, you can safely and efficiently install, activate, and configure the server, as well as resolve the most common issues.

If you have any questions or problems, please contact our technical support at 00 800 121 1654 or visit our knowledge base: /category/windows-server-2025. You can also email us at [email protected] for further assistance.