System.IO.FileLoadException when running function ("Microsoft.IdentityModel.Tokens")

Invocation ID: 4a8b83e2-2ad0-4f70-a13b-c41295cf6f17 Timestamp: 2018-02-21T16:25:54.224 Function App version (1.0 or 2.0-beta): 2.0-beta

Repro steps

Create a .net core project that contains the function to run.

Add package reference to project like below: <PackageReference Include="Microsoft.IdentityModel.Tokens" Version="5.2.1" />

Call a method that uses the above package and its dependancies.

Example method

public string CreateJWTToken(ClaimsIdentity identity)
{
    string _algorithm = "http://www.w3.org/2001/04/xmldsig-more#hmac-sha256";
    string _digest = "http://www.w3.org/2001/04/xmlenc#sha256";
    var symmetricKey = Encoding.UTF8.GetBytes("<somekey>");
    var securityKey = new SymmetricSecurityKey(symmetricKey);
    var credentials = new SigningCredentials(securityKey, _algorithm, _digest);

    var tokenDescriptor = new SecurityTokenDescriptor();
    tokenDescriptor.Subject = identity;
    tokenDescriptor.Issuer = "";
    tokenDescriptor.Audience = "";
    tokenDescriptor.SigningCredentials = credentials;

    var tokenHandler = new JwtSecurityTokenHandler();
    var token = tokenHandler.CreateToken(tokenDescriptor);
    return tokenHandler.WriteToken(token);
}

Expected behavior

Assembly resolved and jwt token created successfully

Actual behavior

Exception is thrown: System.IO.FileLoadException

Could not load file or assembly ‘Microsoft.IdentityModel.Tokens, Version=5.2.1.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35’. Could not find or load a specific file. (Exception from HRESULT: 0x80131621)

Known workarounds

None

Related information

1. This fails both on my local functions host and when running in Azure.
2. I have inspected the bin folder in both cases and the assembly exists there right along side my application dll.
3. I have tried to recreate in a .net core console app and all work well there.

Provide any related information

• Programming language used C#

Binding

{
  "generatedBy": "Microsoft.NET.Sdk.Functions.Generator-1.0.8",
  "configurationSource": "attributes",
  "bindings": [
    {
      "type": "httpTrigger",
      "route": "Authenticate",
      "methods": [
        "post"
      ],
      "authLevel": "anonymous",
      "name": "request"
    }
  ],
  "disabled": false,
  "scriptFile": "../bin/MyProject.dll",
  "entryPoint": "MyProject.Functions.AuthenticateFunction.Run"
}

[pizerg]

I’m running into the same issue with Microsoft.IdentityModel.Tokens Version=“5.2.2”.

As a workaround I downgraded to version 5.1.4 which loads without problems

[fabiocav]

As mentioned. Work is in progress and fixes will be deployed with the next release. Leaving this open and moving to Sprint 25 for validation