Suave not working in heroku

[ImaginaryDevelopment]

from my repository https://github.com/ImaginaryDevelopment/mono-suave (builds and deploys back to github releases from appveyor just fine)

-----> SuaveFramework app detected
-----> Downloading mono to /app/tmp/cache/heroku-18/vendor
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
0 0 1397k 0 0:00:05 --:--:-- 0:00:05 1397k
-----> Copying /app/tmp/cache/heroku-18/vendor/mono to /tmp/build_52d7eedd961e2d8c75c5bce0083d1fc2/vendor
-----> Linking /tmp/build_52d7eedd961e2d8c75c5bce0083d1fc2/vendor/mono --> /app
-----> Setting envvars
-----> Importing trusted root certificates
-----> paket.lock found, restoring packages with paket
Paket version 5.120.0
Downloading FSharp.Core 4.6.2
Downloading Suave 2.5.3
Performance:

• Disk IO: 1 second
• Average Download Time: 1 second
• Number of downloads: 2
• Average Request Time: 1 second
• Number of Requests: 2
• Runtime: 5 seconds
  -----> packages.config found, installing dependencies with nuget
  Unhandled Exception:
  System.MissingMethodException: Method 'AppContext.SetSwitch' not found.
  [ERROR] FATAL UNHANDLED EXCEPTION: System.MissingMethodException: Method 'AppContext.SetSwitch' not found.
  ! Push rejected, failed to compile SuaveFramework app.
  ! Push failed

From the button on suave.io

-----> SuaveFramework app detected
-----> Downloading mono to /app/tmp/cache/heroku-18/vendor
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
0 0 0 0 --:--:-- --:--:-- --:--:-- 0
-----> Copying /app/tmp/cache/heroku-18/vendor/mono to /tmp/build_c7901ccdfba52edb511cc04513bcb0de/vendor
-----> Linking /tmp/build_c7901ccdfba52edb511cc04513bcb0de/vendor/mono --> /app
-----> Setting envvars
-----> Importing trusted root certificates
-----> paket.dependencies found, installing packages with paket
Paket version 5.120.0
Resolving packages for group Main:

• Suave 2.5.3
• FSharp.Core 4.6.2
  Locked version resolution written to /tmp/build_c7901ccdfba52edb511cc04513bcb0de/paket.lock
  Installing into projects:
• Creating model and downloading packages.
  Downloading FSharp.Core 4.6.2
  Downloading Suave 2.5.3
  Performance:
• Resolver: 5 seconds (1 runs)
  • Runtime: 209 milliseconds
  • Blocked (retrieving package details): 3 seconds (2 times)
  • Blocked (retrieving package versions): 1 second (2 times)
• Disk IO: 1 second
• Average Download Time: 505 milliseconds
• Number of downloads: 2
• Average Request Time: 1 second
• Number of Requests: 17
• Runtime: 8 seconds
  -----> Compiling app.fsx
  F# Compiler for F# 4.1
  Freely distributed under the Apache 2.0 Open Source License
  /tmp/build_c7901ccdfba52edb511cc04513bcb0de/app.fsx(10,1): warning FS0211: The search directory '/tmp/build_c7901ccdfba52edb511cc04513bcb0de/packages/Suave/lib/net40' could not be found
  /tmp/build_c7901ccdfba52edb511cc04513bcb0de/app.fsx(11,1): error FS0078: Unable to find the file 'packages/Suave/lib/net40/Suave.dll' in any of
  /tmp/build_c7901ccdfba52edb511cc04513bcb0de/vendor/mono/lib/mono/4.5-api
  /tmp/build_c7901ccdfba52edb511cc04513bcb0de/vendor/mono/lib/mono/4.5-api/Facades
  /tmp/build_c7901ccdfba52edb511cc04513bcb0de/vendor/mono/lib/mono/4.5
  /tmp/build_c7901ccdfba52edb511cc04513bcb0de/vendor/mono/lib/mono/4.5/Facades
  /tmp/build_c7901ccdfba52edb511cc04513bcb0de
  /app/mono/lib/mono/4.5
  ! Push rejected, failed to compile SuaveFramework app.
  ! Push failed

my app's code

let routing =
    choose[
        path "/" >=> OK "hello"
    ]
[<EntryPoint>]
let main argv =
    printfn "%A" argv
    0 // return an integer exit code

[ademar]

At first glance I think we need to upgrade the mono version in the buildpack.

https://github.com/SuaveIO/mono-script-buildpack/blob/master/bin/compile#L12

[ademar]

On a second though I think is time to upgrade the Heroku script to use dotnet core instead of mono.

[tonyx]

I have the same problem.