DiagCode: 3003#7106 .NET Framework 4.8

[cgrosjea]

BotMedia SDK native media engine does not bind UDP port under .NET Framework 4.8

SDK Version: Microsoft.Skype.Bots.Media 1.31.0.225
Graph Communications SDK: Latest
OS: Windows Server (x64)
Runtime tested: .NET Framework 4.8 (fails), .NET 6 (works)

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Summary

The BotMedia native media engine silently fails to initialize when hosted in a .NET Framework 4.8 process. The UDP media port is never bound, causing Teams to drop the call with DiagCode: 3003#7106 after ~4 seconds. The exact same configuration and code works correctly on .NET 6 on the same machine.

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Reproduction Steps

1. Take a working .NET 6 Teams compliance recording bot (Kestrel, call.AnswerAsync(mediaSession))
2. Port it to .NET Framework 4.8 using OWIN for HTTP hosting
3. Keep identical MediaPlatformSettings, AudioSocketSettings, CommunicationsClientBuilder configuration
4. Run and place a call

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Observed Behavior

Signaling works correctly:

• Webhook received ✅
• OnIncomingCall fires ✅
• CreateMediaSession succeeds ✅
• AnswerAsync completes without exception ✅
• state=establishing webhook received ✅

But media never starts:

• UDP port is never bound by the media platform
• Teams drops call after ~4 seconds with DiagCode: 3003#7106
• AudioMediaReceived event never fires
• 0 bytes recorded

Confirmed via UDP listener check immediately after builder.Build():

[DIAG] UDP 8445 is NOT bound - media platform silently failed!
[DIAG] All UDP ports bound by this process: (none in range 8000-9000)

Same check on .NET 6 version:

[DIAG] UDP 8445 IS bound on 0.0.0.0 - media platform OK

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MediaPlatformSettings (identical in both versions)

var mediaPlatformSettings = new MediaPlatformSettings
{
    ApplicationId = APP_ID,
    MediaPlatformInstanceSettings = new MediaPlatformInstanceSettings
    {
        ServiceFqdn             = "bot.example.com",
        CertificateThumbprint   = CERT_THUMBPRINT,
        InstanceInternalPort    = 8445,
        InstancePublicIPAddress = IPAddress.Parse("x.x.x.x"),
        InstancePublicPort      = 8445,
    }
};

var builder = new CommunicationsClientBuilder("PolicyRecordingBot", APP_ID, logger);
builder.SetAuthenticationProvider(authProvider);
builder.SetNotificationUrl(notificationUri);
builder.SetMediaPlatformSettings(mediaPlatformSettings);
builder.SetServiceBaseUrl(new Uri("https://graph.microsoft.com/v1.0"));

var client = builder.Build();

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Error Codes Observed

Condition	DiagCode
UDP not bound (pure media failure)	3003#7106
SDK throws during answer processing	500#1203003

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The BotMedia SDK ships native C++ DLLs that appear to depend on the .NET Core runtime hosting APIs (coreclr.dll) for initialization. When loaded into a .NET Framework 4.8 process, the native media engine silently fails to start — no exception is thrown, no error is logged, but the UDP port is never bound and no media is processed.

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Questions

1. Is Microsoft.Skype.Bots.Media officially supported on .NET Framework 4.8, or is .NET Core / .NET 6+ a hard requirement?
2. Is there a supported way to host the BotMedia SDK inside a .NET Framework 4.8 process?
3. If .NET Framework 4.8 is not supported, is out-of-process hosting (separate .NET 6 executable communicating via IPC) the recommended integration pattern for mixed-runtime environments?
4. Is there any initialization API we should be calling explicitly to start the media platform that we may be missing?

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[ssulzer]

Hi @cgrosjea
Have you followed the special setup instructions in the SDK's readme.txt file concerning running on .NET Framework?
There was a breaking change regarding .NET Framework starting with version 1.28 of the media SDK. The notes for SDK version 1.31 included an addendum. Combining those two together:

* IMPORTANT!

  !!! Breaking Change !!! 
  =======================
  This SDK requires modifying your existing startup script prior to service startup.

  This is applicable only when running the SDK on .NET Framework.
  No change is needed when running on .NET 6 or later.

  Background:
  ==========
  Prior to startup, services generally run some commands to bind the IP 
  and listening ports to an SSL cert. Additionally, services also add HTTP
  registrations to the IP/Port so that the Windows HTTP.sys server routes
  incoming requests to the right service on the VM.
  This is typically done with the help of netsh command-line utility. 

  Setup Instructions:
  ==================
  Add the following extra commands to the startup or entrypoint script:

  # %InstanceMediaControlPort% is the internal media control listening port
  # that is configured when the `MediaPlatform` is initialized;
  # i.e., it is the `InstanceInternalPort` property on the `MediaPlatformInstanceSettings`

  # Delete ssl cert bindings
  netsh http delete sslcert ipport=%InstanceIpAddress%:%InstanceMediaControlPort%
  
  # Delete http registrations
  netsh http delete urlacl url=https://+:%InstanceMediaControlPort%/
  
  # Bind ssl cert to the IP/Port and enable client certificate negotiation
  # The "netsh http add sslcert" command should  also specify a
  # "clientcertnegotiation=enable" parameter, otherwise a call setup
  # failure may occur.
  netsh http add sslcert ipport=%InstanceIpAddress%:%InstanceMediaControlPort% "appid={00000000-0000-0000-0000-000000000001}" cert=%ServerCertificate% clientcertnegotiation=enable
  
  # Add http registrations
  netsh http add urlacl url=https://+:%InstanceMediaControlPort%/ user="NT AUTHORITY\NETWORK SERVICE"