"The library hostfxr.dll was found, but loading it from C:\Program Files (x86)\dotnet\host\fxr\3.1.1\hostfxr.dll failed"

[johndaintree]

> >dotnet --list-sdks
> Failed to load the dll from [C:\Program Files (x86)\dotnet\host\fxr\3.1.1\hostfxr.dll], HRESULT: 0x800700C1
> The library hostfxr.dll was found, but loading it from C:\Program Files (x86)\dotnet\host\fxr\3.1.1\hostfxr.dll failed
> 
> Installing .NET Core prerequisites might help resolve this problem.
>      https://go.microsoft.com/fwlink/?linkid=798306

I've just installed both 64 and 32 bit version of 3.1.101 from https://dotnet.microsoft.com/download/dotnet-core/3.1

The 64 bit version is fine, however the 32 bit version gives the above message.

I'm on Windows 10 (1909, 18363.592), so I think I have all the pre-requisites (that is to say there are none).

How can fix this?

[ClearScriptLib]

We're seeing the same issue on Windows 10 1903, affecting only the 32-bit version of .NET Core.

Strangely, it worked yesterday, but last night's Patch Tuesday reboot seems to have broken it.

[johndaintree]

Seems to be ok now in 3.1.102.

[szszoke]

I have this issue as well. I am running Windows 10 1903 Build 18362.239.

I tried both with 3.1.200 and 3.1.201.

[minan61]

Same issue here, worked 10 mins ago, but got stuck on whatever reason

[adambarath]

By installing KB2533623 update will solve the problem for Windows 7 deployments: https://support.microsoft.com/en-gb/help/2533623/microsoft-security-advisory-insecure-library-loading-could-allow-remot

[doghappy]

By installing KB2533623 update will solve the problem for Windows 7 deployments: https://support.microsoft.com/en-gb/help/2533623/microsoft-security-advisory-insecure-library-loading-could-allow-remot

Today, I could not download it and got a 404 page. dotnet/docs#20459

[doghappy]

KB3063858 fixed the problem for me!

32-bit: https://www.microsoft.com/en-us/download/details.aspx?id=47409
64-bit: https://www.microsoft.com/en-us/download/details.aspx?id=47442

—— https://www.reddit.com/r/windows/comments/ik7sp7/does_anybody_have_the_kb2533623_update_for/

[aolszowka]

Getting burned by this in Windows Server 2019 (1809) Updates didn't seem to do much for me, did anyone figure out what the actual root cause for this is?

[ccornici]

Getting the same exact thing when creating a WPF APPX bundle, installing it and running it, the app just exits and in Event Viewer I got

Description: A .NET Core application failed.
Application: myapp.exe
Path:  C:\Program Files\WindowsApps\myapp\myapp.exe
Message: Failed to load the dll from [C:\Program Files\WindowsApp\myapp\hostfxr.dll], HRESULT: 0x800700C1
The library hostfxr.dll was found, but loading it from C:\Program Files\WindowsApp\myapp\hostfxr.dll failed
  - Installing .NET Core prerequisites might help resolve this problem.
     https://go.microsoft.com/fwlink/?linkid=798306

When I try building, installing & running a different app, which is also build on .NET Core 3.1 and uses similar nugets etc it runs without any issues

I tested on a different machine and the same issue happens.....

[ccornici]

I deleted the bin & obj folders from the projects and now it works, so I assume it's yet another VS 2019 bug....

[ccornici]

Now it doesn't work anymore again even after I delete the folders above :)

[confessore]

I get unexpected behaviors with hostfxr compiled for x86 but everything for x64 works like a dream!

I'm spinning up the host after injecting it into an active process.

on x64 inside of an x64 process, everything works great

on x86 inside of an x86 process, it works as intended every 1/20 times (probably has something to do with address spaces)

there's something nutty going on with x86

[KirillOsenkov]

This is most definitely still an issue:

• install .NET SDK 64-bit
• install .NET SDK 32-bit
• run an app targeting netcoreapp3.1 and compiled with PublishSingleFile

Failed to load the dll from [C:\Program Files (x86)\dotnet\host\fxr\6.0.0-rc.2.21480.5\hostfxr.dll], HRESULT: 0x800700C1
The library hostfxr.dll was found, but loading it from C:\Program Files (x86)\dotnet\host\fxr\6.0.0-rc.2.21480.5\hostfxr.dll failed

Why is it trying to load the x86 hostfxr? Shouldn't it be trying the 64-bit one?

[RaulSebastian]

This is most definitely still an issue:

* install .NET SDK 64-bit

* install .NET SDK 32-bit

* run an app targeting netcoreapp3.1 and compiled with PublishSingleFile

Failed to load the dll from [C:\Program Files (x86)\dotnet\host\fxr\6.0.0-rc.2.21480.5\hostfxr.dll], HRESULT: 0x800700C1
The library hostfxr.dll was found, but loading it from C:\Program Files (x86)\dotnet\host\fxr\6.0.0-rc.2.21480.5\hostfxr.dll failed

Why is it trying to load the x86 hostfxr? Shouldn't it be trying the 64-bit one?

got the same issue, this should be adressed

[NCLnclNCL]

This is most definitely still an issue:

* install .NET SDK 64-bit

* install .NET SDK 32-bit

* run an app targeting netcoreapp3.1 and compiled with PublishSingleFile

Failed to load the dll from [C:\Program Files (x86)\dotnet\host\fxr\6.0.0-rc.2.21480.5\hostfxr.dll], HRESULT: 0x800700C1
The library hostfxr.dll was found, but loading it from C:\Program Files (x86)\dotnet\host\fxr\6.0.0-rc.2.21480.5\hostfxr.dll failed

Why is it trying to load the x86 hostfxr? Shouldn't it be trying the 64-bit one?

got the same issue, this should be adressed

yes it will errors if dotnet run -a x86 in dotnet runtime 64 bit