404 /signalr/negotiate for deployed app in Azure - azure

Question

SignalR works on localhost but doesn't work when is deployed in Azure
Asp.net Core 1.0.0 (.Net Framework 4.6.1)
SignalR.Core 2.2.1
public static void UseSignalR2(this IApplicationBuilder app)
{
app.UseAppBuilder(appBuilder => {
appBuilder.MapSignalR(new HubConfiguration());
});
GlobalHost.HubPipeline.AddModule(new ErrorHandlingPipelineModule());
GlobalHost.HubPipeline.AddModule(new LoggingPipelineModule());
}
SignalR.js 2.2.1 with default settings
$.connection.hub.url = '/signalr';
Expected behavior
200 for url:
https://(name).azurewebsites.com/signalr/negotiate?clientProtocol=1.5&connectionData=%5B%7B%22name%22%3A%22productsimporthub%22%7D%5D&_=1472811629592
Actual behavior
/signalr/negotiate - on localhost returns 200 but for deployed app in azure returns 404
/signalr - works on both - Protocol error: Unknown transport.
/signalr/hubs - works on both - returns the SignalR js correctly

Answer 1

To find out the real cause of the issue you need to navigate to the negotiate url, and look for the response.
If the response tells you something about a 'CryptographicException: The data protection operation was unsuccessful...'. This is how to fix it.
1) Create a custom IDataProtectionProvider
2) Configure signalr
internal class MachineKeyProtectionProvider : IDataProtectionProvider
{
public IDataProtector Create(params string[] purposes)
{
return new MachineKeyDataProtector(purposes);
}
}
internal class MachineKeyDataProtector : IDataProtector
{
private readonly string[] _purposes;
public MachineKeyDataProtector(string[] purposes)
{
_purposes = purposes;
}
public byte[] Protect(byte[] userData)
{
//return MachineKey.Protect(userData, _purposes);
return userData;
}
public byte[] Unprotect(byte[] protectedData)
{
//return System.Web.Security.MachineKey.Unprotect(protectedData, _purposes);
return protectedData;
}
}
I use katana extension methods to bridge the IAppBuilder to IApplicationBuilder.
This allows your owin middleware to connect to asp.net core. It is important to use the RunSignalr method
app.UseAppBuilder(appBuilder =>
{
appBuilder.SetDataProtectionProvider(new MachineKeyProtectionProvider());
appBuilder.Map("/signalr", map =>
{
var hubConfiguration = new HubConfiguration
{
EnableDetailedErrors = true
};
map.RunSignalR(hubConfiguration);
});
});