Error: Failed to complete negotiation with the server: Error: Not Found

Question

I\'m using SignalR with ASP.NET Boilerplate .NET Core 3.1 but I encounterd this problem

Error: Failed to complete negotiation with the server: Error: Not Found<

Answer 1

That error is for connecting to /signalr for AbpCommonHub, used by ABP for real-time notifications.
ABP document: https://aspnetboilerplate.com/Pages/Documents/Notification-System#real-time-notifications

You should restore endpoints.MapHub<AbpCommonHub>("/signalr");.

app.UseEndpoints(endpoints =>
{
    endpoints.MapHub<AbpCommonHub>("/signalr"); // Restore this
    endpoints.MapHub<MyChatHub>("/signalr-myChatHub");
    endpoints.MapControllerRoute("default", "{controller=Home}/{action=Index}/{id?}");
    endpoints.MapControllerRoute("defaultWithArea", "{area}/{controller=Home}/{action=Index}/{id?}");
});

By the way, you can remove app.UseSignalR(...);, which has been deprecated in favour of app.UseEndpoints(...);.