Cannot run existing projects on simulator after upgrading MonoTouch

I just upgraded Monotouch to latest 4.0 and MonoFramework to 2.10.1_3.macos10 and now none of my existing projects run on simulator. If I create a new project, it runs fine. How can I fix this?

If I click on the Run button in Monodevelop, the build completes successfully, but at the Application Output window I get this error:

Error connecting stdout and stderr (127.0.0.1:10001)
Couldn't register com.yourcompany.textproblem with the bootstrap server. Error: unknown error code.
This generally means that another instance of this process was already running or is hung in the debugger.Stacktrace:

  at (wrapper managed-to-native) MonoTouch.UIKit.UIApplication.UIApplicationMain (int,string[],intptr,intptr) <IL 0x0009f, 0xffffffff>
  at MonoTouch.UIKit.UIApplication.Main (string[],string,string) [0x00038] in /Users/plasma/Source/iphone/monotouch/UIKit/UIApplication.cs:26
  at MonoTouch.UIKit.UIApplication.Main (string[]) [0x00000] in /Users/plasma/Source/iphone/monotouch/UIKit/UIApplication.cs:31
  at TextProblem.Application.Main (string[]) [0x00000] in /Users/admin/Projects/TextProblem/TextProblem/Main.cs:14
  at (wrapper runtime-invoke) <Module>.runtime_invoke_void_object (object,intptr,intptr,intptr) <IL 0x00050, 0xffffffff>

Native stacktrace:

    0   TextProblem                         0x000d0db5 mono_handle_native_sigsegv + 343
    1   TextProblem                         0x0013afad sigabrt_signal_handler + 116
    2   libSystem.B.dylib                   0x9027246b _sigtramp + 43
    3   ???                                 0xffffffff 0x0 + 4294967295
    4   libSystem.B.dylib                   0x902ff89d raise + 26
    5   libSystem.B.dylib                   0x903159bc abort + 93
    6   GraphicsServices                    0x03edd558 GSRegisterPurpleNamedPort + 323
    7   GraphicsServices                    0x03edd715 GSEventInitialize + 220
    8   UIKit                               0x01c17229 UIApplicationMain + 643
    9   ???                                 0x09e09744 0x0 + 165713732
    10  ???                                 0x09e0967a 0x0 + 165713530
    11  ???                                 0x07ff2b96 0x0 + 134163350
    12  ???                                 0x07ff2ae2 0x0 + 134163170
    13  ???                                 0x07ff2b6d 0x0 + 134163309
    14  TextProblem                         0x0000f5c7 mono_jit_runtime_invoke + 1332
    15  TextProblem                         0x001ed281 mono_runtime_invoke + 137
    16  TextProblem                         0x001ef968 mono_runtime_exec_main + 669
    17  TextProblem                         0x001eed52 mono_runtime_run_main + 843
    18  TextProblem                         0x000a3153 mono_jit_exec + 200
    19  TextProblem                         0x002a16b8 main + 4155
    20  TextProblem                         0x00002949 _start + 208
    21  TextProblem                         0x00002878 start + 40

Debug info from gdb:

/tmp/mono-gdb-commands.C9e16B:1: Error in sourced command file:
unable to debug self

=================================================================
Got a SIGABRT while executing native code. This usually indicates
a fatal error in the mono runtime or one of the native libraries 
used by your applicatio开发者_如何学Gon.
=================================================================

Try resetting the simulator. iOS Simulator -> Reset Content and Settings. Note that this will reset the simulator to its default state.

You have a process hung in the simulator, a reboot should resolve this.