failed load hostfxr.dll at .net9 self-container app on win10,win7

Question

i write a client app with .net9 vs2026, and publish with self-container.
but it can't be run when i double-click on (win10,win7) part of my client machine.
i look eventlog and get this. how to reslove this?

i got a information for win7, install a fix, see to https://www.catalog.update.microsoft.com/Search.aspx?q=KB4457144
but win10?

bug info:
Description: A .NET application failed.

Application: Ossi.App.exe

Path: D:\新治超检测站级系统\Ossi.App\Ossi.App.exe

Message: Failed to load the dll from [D:\新治超检测站级系统\Ossi.App\hostfxr.dll], HRESULT: 0x80070017

The library hostfxr.dll was found, but loading it from D:\新治超检测站级系统\Ossi.App\hostfxr.dll failed

• Installing .NET prerequisites might help resolve this problem. https://go.microsoft.com/fwlink/?linkid=798306

Failed to resolve hostfxr.dll [D:\新治超检测站级系统\Ossi.App\hostfxr.dll]. Error code: 0x80008082

Answer 1

Thank you for reaching out.

The error Failed to load hostfxr.dll (HRESULT: 0x80070017) means the app cannot read the required runtime file. This usually happens because:

• Files in the published folder are corrupted or incomplete.
• Antivirus or security services block or modify files after first run.
• On Windows 7, missing SHA‑2 support (KB4457144 update) prevents .NET 9 apps from running.
• Disk or copy errors during deployment.

Steps you can try

1. Verify published files
   • Re-publish the app as Self-contained for the correct OS architecture (x64/x86).
   • Copy files using a reliable method (avoid partial ZIP extraction).
2. Check OS prerequisites
   • Windows 7: Install https://support.microsoft.com/help/4457144 for SHA‑2 code signing support.
   • Windows 10: No extra patch needed, but ensure latest updates are installed.
3. Run as Administrator
   • Right-click the .exe → Run as Administrator to avoid permission issues.
4. Disable antivirus temporarily
   • Some security tools block hostfxr.dll. Test after disabling antivirus/firewall.
5. Repair corrupted files
   • If error persists, delete the app folder and copy fresh files from the publish output.
6. Check Event Viewer logs
   • Look for disk errors or security service interference (Software Protection Service restart).

Tips:

• Always publish with dotnet publish -r win10-x64 --self-contained true.
• Use single-folder deployment and verify integrity before shipping.
• Avoid modifying files after publishing.

Please let us know if you require any further assistance, we’re happy to help.

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