All Products
Search

This Product

    :Resolving .NET Framework 3.5 or language pack installation failures on Windows Server

    Document Center

    :Resolving .NET Framework 3.5 or language pack installation failures on Windows Server

    Last Updated:Jun 21, 2026

    Symptoms

    • Symptom 1: When you install .NET Framework 3.5, the installation fails with the error "Installation of one or more roles, role services, or features failed."

      The error details show that the source files could not be found and identify the failed feature as .NET Framework 3.5 (includes .NET 2.0 and 3.0).

    • Symptom 2: When you switch languages in Control Panel or browse language options in Windows Update, you cannot select or install a language pack.

      For example, on the language options page for Japanese, the message A language pack isn't available appears under Windows display language.

    Cause

    Installation fails with a "source files not found" error because the default Windows Server Update Services (WSUS) update source for the instance lacks the installation files for .NET Framework 3.5 or language packs.

    Solutions

    This topic describes two methods for installing .NET Framework 3.5:

    Ensure the instance has a public IP address before you install .NET Framework 3.5.

    Method 1: Install using Cloud Assistant

    1. Go to ECS console - Cloud Assistant.

    2. On the ECS Instances tab, find the target instance and click Send Remote Command in the Actions column.

    3. Enter the following command and select Run Now. Set Timeout to 6000 seconds or longer. Keep the default settings for other parameters and click Run.

      acs-plugin-manager.exe -e -P Windows_RestoreAndUpdate -p "-ByMedia iso -InstallFeature NetFx3"

    4. Verify the installation. On the Execution Results tab, check the Execution Status of the command.

      If the Execution Status is Finished, click View Output in the Actions column. If the output shows no errors, the installation is successful.

      For Windows Server 2012 R2, if the command fails or returns an error, you may also need to troubleshoot security patch issues.

    Method 2: Manually switch the update source

    GUI

    1. Switch the update source.

      1. Log on to an ECS instance.

        1. Go to ECS console - Instances. In the top-left corner, select the region and resource group for the target instance.

        2. Navigate to the details page of the target instance. Click Connect and select Workbench. Set the connection method to Terminal Connection, enter your username and password, and log on to the graphical terminal.

      2. Right-click the Start 开始图标 icon and click Run. Enter gpedit.msc to open the Local Group Policy Editor.

      3. Configure the local group policy.

        • For Windows Server 2012 R2, Windows Server 2016, Windows Server 2019, or Windows Server 2022:

          1. In the Local Group Policy Editor, navigate to Computer Configuration > Administrative Templates > System.

          2. Double-click Specify settings for optional component installation and component repair. Select Enabled, select the Download repair content and optional features directly from Windows Update instead of Windows Server Update Services (WSUS) checkbox, and then click OK.

            On Windows Server 2012 R2, this checkbox is labeled Contact Windows Update directly to download repair content instead of Windows Server Update Services (WSUS).

        • For Windows Server 2025:

          1. In the Local Group Policy Editor, navigate to Computer Configuration > Administrative Templates > Windows Components > Windows Update > Manage updates offered from Windows Server Update Service.

          2. Double-click Specify source service for specific classes of Windows Updates, select Enabled, set Feature Updates to Windows Update, and then click OK.

      4. Apply the group policy changes.

        Right-click the Start 开始图标 icon and click Run. Enter PowerShell to open a PowerShell window, and then run gpupdate /force to apply the policy immediately.

    2. Install .NET Framework 3.5.

      1. In the lower-left corner, click the Start 开始图标 icon and select Server Manager.

      2. In Server Manager, click Add roles and features.

      3. On the Features page of the wizard, select the .NET Framework 3.5 Features checkbox and follow the wizard prompts to complete the installation.

        For Windows Server 2012 R2, if the installation still fails, you may also need to troubleshoot security patch issues.

    3. (Optional) Restore the WSUS update source.

      If your environment requires updates to be managed through WSUS, run the following commands in PowerShell to restore the original configuration after the installation is complete. 

      Set-ItemProperty -Path 'HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU' -Name UseWUServer -Value 1
Restart-Service -Name wuauserv

    PowerShell CLI

    1. Switch the update source.

      1. Log on to an ECS instance.

        1. Go to ECS console - Instances. In the top-left corner, select the region and resource group for the target instance.

        2. Navigate to the details page of the target instance. Click Connect and select Workbench. Set the connection method to Terminal Connection, enter your username and password, and log on to the graphical terminal.

      2. Right-click the Start 开始图标 icon and click Run. Enter PowerShell to open a PowerShell window, and then run the following commands to switch the update source.

        Set-ItemProperty -Path 'HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU' -Name UseWUServer -Value 0
Restart-Service -Name wuauserv

    2. Install .NET Framework 3.5.

      Dism /Online /Enable-Feature /FeatureName:NetFX3 /All
      If you encounter errors such as 0x800F0906 or 0x800F081F, see .NET Framework 3.5 installation error.
      For Windows Server 2012 R2, if the installation still fails, you may also need to troubleshoot security patch issues.

    3. (Optional) Restore the WSUS update source.

      If your environment requires updates to be managed through WSUS, run the following commands in PowerShell to restore the WSUS update source after the installation is complete. 

      Set-ItemProperty -Path 'HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU' -Name UseWUServer -Value 1
Restart-Service -Name wuauserv

    Related documents

    For instructions on how to install later versions of the .NET Framework, see Install the .NET Framework for developers.