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0x800f081fComponent store source files not foundError codeWidely reported

0x800F081F: The Source Files Could Not Be Found

Updated Oct 23, 2026 · Checked against Microsoft documentation · How this page is made

Quick answer

Error 0x800F081F occurs when Windows attempts to install an optional component or repair system files but cannot find the required binaries in the specified source location. It most frequently appears when enabling .NET Framework 3.5 or running DISM health restoration commands. Pointing Windows directly to a valid installation media source or reconnecting to Windows Update resolves the missing files.

What it means

Windows uses modular packages called Features on Demand for optional components such as .NET Framework 3.5. To keep the initial Windows installation footprint small, the metadata for these packages is present on the storage drive, but the underlying payload binaries are omitted. When an administrator or application requests to turn on one of these features, Windows reaches out to Windows Update or to a designated local installation path to retrieve the missing payload files.

Why the error appears

When error 0x800F081F occurs, the operation fails because the source path specified for component servicing is missing the required binaries, cannot be accessed, or contains files incompatible with the installed Windows build. If an alternate source path is supplied—such as a network folder or a mounted disc image—Windows expects to find the servicing files inside a directory named \sources\sxs. If that directory lacks the specific files, if the user account running the process lacks Read permissions to that location, or if the files are damaged, Windows terminates the task and reports 0x800F081F.

Network and servicing policy conflicts

This error also surfaces in managed network environments where computers are configured to pull updates exclusively from Windows Server Update Services (WSUS). WSUS servers do not always host the optional component payloads that standard Windows Update provides. If Windows is instructed by policy to pull servicing content from an internal server that does not store those files, and the system is blocked from contacting public Windows Update servers, the installation fails because no valid source remains accessible.

Common causes

  • The directory specified by the source path does not contain the servicing files required to install the feature.
  • The user account attempting the installation does not have at least Read permissions to the source folder and its files.
  • The installation files in the source folder are incomplete, corrupted, or built for a different version of Windows.
  • The computer is directed to use Windows Server Update Services (WSUS) instead of Windows Update to download repair and optional component payloads.

How to fix it

Safest and most likely fixes first. Readers' answers to "Did this fix it?" reorder this list over time.

  1. Install using mounted Windows installation media

    Use this fix when you have a Windows installation DVD, USB drive, or mounted ISO file containing the original setup files.

    1. Insert your Windows installation media or double-click your Windows ISO file to mount it as a drive.
    2. Check File Explorer to identify the drive letter assigned to the installation media.
    3. Press Windows Key + X and select Command Prompt (Admin) or Windows Terminal (Admin).
    4. Type Dism /online /enable-feature /featurename:NetFx3 /All /Source:D:\sources\sxs /LimitAccess (replace D: with your media drive letter) and press Enter.
    5. Wait for the progress bar to complete and verify the operation reports success.
    Did this fix it?

  2. Verify folder permissions on the SxS source directory

    Use this fix if your source folder is already present locally or on a network share but DISM reports that files cannot be found.

    1. Open File Explorer and locate the sources folder containing your installation files.
    2. Right-click the sxs folder and select Properties.
    3. Select the Security tab and check whether Read & Execute permissions are allowed.
    4. If Read & Execute is not checked, click Edit, grant your user account Read & Execute and Read permissions, and click OK.
    5. Open Command Prompt as an administrator and retry the installation command.
    Did this fix it?

  3. Configure Group Policy to bypass WSUS for repair content

    Use this fix if your machine is managed by local policies that direct update requests to an internal server lacking component files.

    1. Click Search, type edit group policy, and press Enter to open the Local Group Policy Editor.
    2. Navigate to Computer Configuration, expand Administrative Templates, and select System.
    3. Double-click the setting named Specify settings for optional component installation and component repair.
    4. Select Enabled.
    5. Check the box labeled Contact Windows Update directly to download repair content instead of Windows Server Update Services (WSUS).
    6. Click OK to save the policy change.
    7. Open Command Prompt as an administrator, type gpupdate /force, and press Enter to apply the change immediately.
    Did this fix it?

  4. Run DISM image repair with a validated source

    Use this fix when the error occurs while trying to repair corrupt system files with the restore health command.

    1. Press Windows Key + X and choose Command Prompt (Admin).
    2. Type dism /online /Cleanup-Image /RestoreHealth and press Enter.
    3. If an alternate source is needed, append /Source:wim:D:\sources\install.wim:1 /LimitAccess pointing to your valid installation media.
    4. Allow the tool to scan the component store and verify that repair operations finish successfully.
    Did this fix it?

Is it just you?

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Checked Oct 23, 2026. Refreshed automatically every few days.

Sources

Frequently asked questions

What does error code 0x800F081F mean in Windows?

It means Windows cannot locate the source binary files needed to complete a component installation or repair operation. This happens when the specified directory is missing required files, has restrictive access permissions, or holds incompatible files.

Why does .NET Framework 3.5 fail with error 0x800F081F?

.NET Framework 3.5 is a Feature on Demand whose actual binary payloads are not kept in the default Windows image. If Windows cannot download these files through Windows Update or find them inside a provided sources\sxs directory, the setup stops with this code.

Where are the SxS source files located on Windows installation media?

On a standard Windows installation DVD or mounted ISO image, the required component files are located in the sources\sxs folder directly off the root of the media drive.

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