2026-03 Security download failed

Question

Download failed with error code 0x800f0805. Could you advise why it is happening?

Answer 1

Hi Manpreet Bedi,

Your system may have corrupt files, please scan your system by following commands using Command Prompt (Run as administrator):

DISM /Online /Cleanup-Image /RestoreHealth
sfc /scannow

Please reboot your computer after the task has completed.

Then you may follow this article to troubleshoot the Windows update: Windows Update Troubleshooter - Microsoft Support.

Alternatively, you may manually download the update package to install through Microsoft Update Catalog. Just enter the KB you need to Search form then choose the package right for your system.

I hope that above information is helpful to you.

Answer 2

Hi, good day!

What specific update are you trying to install?

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Please let me know if you have tried the methods below.

• Make sure Windows Update and Background Intelligent Transfer services are available and running. Press Windows key+R to open Run then type: services.msc Press Enter to open Services app Double-click Background Intelligent Transfer Service. If the Startup status lists Stopped, click Start and then click OK. If the status is Running, right click then select Restart Double-click Windows Update. If the Startup status lists Stopped, click Start and then click OK. If the status is Running, right click then select Restart
• Reset Windows Update components manually  https://www.elevenforum.com/t/reset-windows-update-in-windows-11.3808/ After that, restart your computer

If the issue persists, open Settings > System > Recovery.

Few things to check on the PC

• Unplug all external peripherals except for the Mouse, Keyboard, and LAN cable before starting
• Disable or uninstall any third-party Antivirus program to prevent it from interfering with the upgrade

Under Fix problems using Windows Update, click Reinstall Now

Once completed, your system will restart.

I look forward to receiving your update and I'm willing to collaborate with you till we resolve the issue. Do keep me informed by clicking "Add comment" below.

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Answer 3

Error code 0x800f0805 indicates that the specific Windows package is not recognized as a valid Windows package. In the documented scenario, this happens when a required Windows component package entry is missing from the registry under the Component-Based Servicing (CBS) configuration. When that package entry is missing or corrupted, Windows Update or servicing tools (like DISM/Server Manager) cannot correctly identify or work with the update package, and operations such as listing or installing features/updates fail with 0x800f0805.

In the referenced case, the missing registry value is under: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\ComponentBasedServicing\PackageIndex\System for the Microsoft-Windows-Foundation-Package~31bf3856ad364e35~amd64~~<Image Version> entry. If a similar CBS/package-index inconsistency exists on the system, it can cause update installation (including a 2026-03 security update) to fail with 0x800f0805.

A documented remediation is to recreate the missing Microsoft-Windows-Foundation-Package~31bf3856ad364e35~amd64~~<Image Version> registry value with the correct data (for example, 10.0.14393.0 with value data 0x00000000), using a working machine with the same OS build as a reference. This restores CBS’s ability to recognize the package so servicing operations can proceed.

Because editing the registry is sensitive and can affect system stability, any such change should be done carefully and only if the environment matches the documented scenario (same key path and missing value).

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References:

• Error 0x800f0805 when Server Manager and DISM fail to list the available features