Json.Net causing debugging issues

SikkuDevelopersSikkuDevelopers USMember
edited November 2014 in Cross Platform with Xamarin

I am having alot of issues with remote debugging iOS from Visual Studio when I make calls to Json.net. To be clear, the operations themselves work just fine, but they cause the debugger to disconnect at application startup which is making for a real headache. Here is a code snippet example:

This works fine , but causes the debugger to end the session when the app launches:

    var resp = response.Result.Content.ReadAsStringAsync().Result;
            var x = JsonConvert.DeserializeObject(resp);

Same with something more explicit:

    var resp = response.Result.Content.ReadAsStringAsync().Result;
           Dictionary<string, object> values = JsonConvert.DeserializeObject<Dictionary<string, object>>(resp);

Removing the call to JsonConvert , means that the debugger does not crash:

    var resp = response.Result.Content.ReadAsStringAsync().Result;
           // var x = JsonConvert.DeserializeObject(resp);

The exception thrown is:

Debugger lost connection to the running application. Likely this means the application terminated unexpectedly.

Mono.Debugger.Soft.VMDisconnectedException: Exception of type 'Mono.Debugger.Soft.VMDisconnectedException' was thrown.
at Mono.Debugger.Soft.Connection.SendReceive(CommandSet command_set, Int32 command, PacketWriter packet)
at Mono.Debugger.Soft.Connection.Assembly_GetName(Int64 id)
at Mono.Debugger.Soft.AssemblyMirror.GetName()
at Mono.Debugging.Soft.SoftDebuggerSession.UpdateAssemblyFilters(AssemblyMirror asm)
at Mono.Debugging.Soft.SoftDebuggerSession.HandleAssemblyLoadEvents(AssemblyLoadEvent[] events)
at Mono.Debugging.Soft.SoftDebuggerSession.HandleEventSet(EventSet es)
at Mono.Debugging.Soft.SoftDebuggerSession.EventHandler()

Which this seems to be telling me there is something about the assembly that mono does not like , but not sure at all how to go about remedying this.

I have Newtonsoft.Json 6.0 installed via Nuget and referenced by both projects. The fact that the code works correctly seems to indicate that the correct libraries are there.

Anyone having a similar issue and figure out how to get around it?




  • KMullinsKMullins USMember, Xamarin Team Xamurai

    Hi @SikkuDevelopers‌,

    Of late I've been using SimpleJson as a replacement for the Newtonsoft.Json because: a) I can embed it directly in my project without need for a 3rd party library, b) I can debug trace into it.

    It has the same calling structure as the Newtonsoft parser so I could use it without code change otherwise. I do however make one change to SimpleJson, it initially is case sensitive and I turn that off to totally match Newtonsoft.Json's functionality.

    Here is the bit I modify:

    /// <summary>
        /// Initializes a new instance of <see cref="JsonObject"/>.
        /// </summary>
        public JsonObject()
            // KKM 08/01/2014 - Forced dictionary to be case insensitive
            // _members = new Dictionary<string, object>();
            _members = new Dictionary<string, object>(StringComparer.OrdinalIgnoreCase);

    You can install SimpleJson from NuGet. You could always use it to see what the issue is and then switch back to Newtonsoft.Json if you like.

    Hope this helps,


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