LibUV error -14 EFAULT Bad address is system call argument

[mvkara]

I'm trying to evaluate Kestrel in my application and am getting faults when Kestrel I think is trying to bind to an address and failing at the LibUV layer. I have LibUV 1.10.1 installed.

The error I'm getting is:

System.AggregateException: One or more errors occurred. ---> Microsoft.AspNetCore.Server.Kestrel.Internal.Networking.UvException: Error -14 EFAULT bad address in system call argument
--- End of inner exception stack trace ---
at System.Threading.Tasks.Task.ThrowIfExceptional (System.Boolean includeTaskCanceledExceptions) [0x00014] in <8f2c484307284b51944a1a13a14c0266>:0
at System.Threading.Tasks.Task.Wait (System.Int32 millisecondsTimeout, System.Threading.CancellationToken cancellationToken) [0x00052] in <8f2c484307284b51944a1a13a14c0266>:0
at System.Threading.Tasks.Task.Wait () [0x00000] in <8f2c484307284b51944a1a13a14c0266>:0
at Microsoft.AspNetCore.Server.Kestrel.Internal.KestrelEngine.CreateServer (Microsoft.AspNetCore.Server.Kestrel.ServerAddress address) [0x00144] in <43555eec0dc34d2abb4f01227fa5a2e9>:0
---> (Inner Exception #0) Microsoft.AspNetCore.Server.Kestrel.Internal.Networking.UvException: Error -14 EFAULT bad address in system call argument<---

[ERROR] FATAL UNHANDLED EXCEPTION: System.AggregateException: One or more errors occurred. ---> Microsoft.AspNetCore.Server.Kestrel.Internal.Networking.UvException: Error -14 EFAULT bad address in system call argument
--- End of inner exception stack trace ---
at System.Threading.Tasks.Task.ThrowIfExceptional (System.Boolean includeTaskCanceledExceptions) [0x00014] in <8f2c484307284b51944a1a13a14c0266>:0
at System.Threading.Tasks.Task.Wait (System.Int32 millisecondsTimeout, System.Threading.CancellationToken cancellationToken) [0x00052] in <8f2c484307284b51944a1a13a14c0266>:0
at System.Threading.Tasks.Task.Wait () [0x00000] in <8f2c484307284b51944a1a13a14c0266>:0
at Microsoft.AspNetCore.Server.Kestrel.Internal.KestrelEngine.CreateServer (Microsoft.AspNetCore.Server.Kestrel.ServerAddress address) [0x00144] in <43555eec0dc34d2abb4f01227fa5a2e9>:0
---> (Inner Exception #0) Microsoft.AspNetCore.Server.Kestrel.Internal.Networking.UvException: Error -14 EFAULT bad address in system call argument<---

Not sure if this is a new bug or something I've done wrong here. Any help would be appreciated.

My app code looks like

WebHostBuilder()
            .UseUrls("http://127.0.0.1:8083")
            .UseKestrel()
            .UseStartup<Startup>()
            .Build()
            .Run()

[davidfowl]

Can you be more specific? What OS? What do you mean you have libuv "installed". It comes with .NET Core, did you install your own copy manually?

[mvkara]

Sure - using Debian Jessie with Mono 4.6.2.16. Wasn't aware .NET Core shipped with LibUV -tried remvoing my LibUV and using that Net Core one via the LD_LIBRARY_PATH and get the same error.

[davidfowl]

ASP.NET Core is unsupported and untested on mono. That said, I don't know why you're getting that error. If you could provide specific repro steps for your setup that would be great.

[moozzyk]

1.10.1 is a patch release but so far we have not tried running Kestrel on Libuv newer than 1.10.0.

[mvkara]

Repro steps:

• Use any Mono version after 4.4.0 (using Docker Mono official image)
• Install LibUV from GitHub releases (or install dotnet and point your LD_LIBRARY_PATH to /usr/share/lib.... in the .NET Core installation if you have one)
• Write a simple Hello World console using the "Microsoft.AspNetCore.Server.Kestrel" nuget pakage app like so:

WebHostBuilder()
        .UseUrls("http://0.0.0.0:8083")
        .UseKestrel()
        .Configure(fun a -> a.Run(fun c -> c.Response.WriteAsync("Hello from Plain Kestrel!")))
        .Build()
.Run()

• Build and run.

I've put a repo with a Dockerfile that reproduces the issue here: https://github.com/mvkra/kestrelexperiment. Any help would be great.

[cesarblum]

@davidfowl I think you meant "Mono is unsupported and untested" 😄

[davidfowl]

Fixed 😄

[gisek]

Fixed 😄

@davidfowl Where can I find the fix? I've got the same problem using latest Mono, latest LibUV, and latest Microsoft.AspNetCore.Server.Kestrel

[davidfowl]

I meant, fixed my typo. Mono still isn't a platform we test on.

[alex-novikov-1990]

My temporary solution:

1. Downgrade Microsoft.AspNetCore.Server.Kestrel to 1.0.3
2. Remove System.Runtime.InteropServices.RuntimeInformation.dll from outputs (because of Can't run with Linux/Mono/dotnet-cli #963)
3. Downgrade Microsoft.Extensions.Logging.Console to 1.0.2 (because 1.1.1 refuses to use System.Runtime.InteropServices.RuntimeInformation.dll from mono, but 1.0.2 - don't 😕)
4. It works! 😌

[davidfowl]

/cc @akoeplinger System.Runtime.InteropServices.RuntimeInformation is on of the main reasons things don't work on mono. Is that resolved yet?

[akoeplinger]

@davidfowl we're blacklisting certain assemblies from certain nuget packages on Mono 4.8+ now because they contain Windows-specific implementation in lib/net45. System.Runtime.InteropServices.RuntimeInformation is one of those on the blacklist, more specifically from the 4.0.0.0 and 4.3.0.0 nuget packages iirc.

Of course this is still a hack and doesn't work e.g. for myget packages etc but it's the best we can do until the packages are fixed (e.g. via dotnet/corefx#15112)