Fiddler will not start on Mojave

[Butch]

When trying to start Fiddler on MacOS 10.14 (Mojave), I see the following crash.  Has anyone gotten Fiddler working on Mojave?

 

 

$ mono Fiddler.exe

WARNING: The Carbon driver has not been ported to 64bits, and very few parts ofWindows.Forms will work properly, or at all
Stacktrace:

  at <unknown> <0xffffffff>
  at (wrapper managed-to-native) System.Windows.Forms.XplatUICarbon.CGDisplayBounds (intptr) [0x00002] in <7cb6368c5ba549ff8a02965fd9de701e>:0
  at System.Windows.Forms.XplatUICarbon.get_WorkingArea () [0x00005] in <7cb6368c5ba549ff8a02965fd9de701e>:0
  at System.Windows.Forms.XplatUICarbon.get_VirtualScreen () [0x00000] in <7cb6368c5ba549ff8a02965fd9de701e>:0
  at System.Windows.Forms.XplatUI.get_VirtualScreen () [0x00000] in <7cb6368c5ba549ff8a02965fd9de701e>:0
  at System.Windows.Forms.Screen..cctor () [0x00034] in <7cb6368c5ba549ff8a02965fd9de701e>:0
  at (wrapper runtime-invoke) object.runtime_invoke_void (object,intptr,intptr,intptr) [0x0001e] in <14f1e720d53a4a6a8800252bec102319>:0
  at <unknown> <0xffffffff>
  at System.Windows.Forms.Form.get_CreateParams () [0x00157] in <7cb6368c5ba549ff8a02965fd9de701e>:0
  at System.Windows.Forms.Control.CreateHandle () [0x0002a] in <7cb6368c5ba549ff8a02965fd9de701e>:0
  at System.Windows.Forms.Form.CreateHandle () [0x00000] in <7cb6368c5ba549ff8a02965fd9de701e>:0
  at System.Windows.Forms.Control.CreateControl () [0x00039] in <7cb6368c5ba549ff8a02965fd9de701e>:0
  at System.Windows.Forms.Control.SetVisibleCore (bool) [0x00057] in <7cb6368c5ba549ff8a02965fd9de701e>:0
  at System.Windows.Forms.Form.SetVisibleCore (bool) [0x00065] in <7cb6368c5ba549ff8a02965fd9de701e>:0
  at System.Windows.Forms.Control.set_Visible (bool) [0x00009] in <7cb6368c5ba549ff8a02965fd9de701e>:0
  at System.Windows.Forms.Control.Show () [0x00000] in <7cb6368c5ba549ff8a02965fd9de701e>:0
  at (wrapper remoting-invoke-with-check) System.Windows.Forms.Control.Show () [0x00031] in <7cb6368c5ba549ff8a02965fd9de701e>:0
  at Fiddler.frmViewer.‹• (string[]) [0x00081] in <09623c708fdb40a483cea147bbea7a7f>:0
  at Fiddler.frmViewer.‡• (string[]) [0x00016] in <09623c708fdb40a483cea147bbea7a7f>:0
  at (wrapper runtime-invoke) <Module>.runtime_invoke_void_object (object,intptr,intptr,intptr) [0x0004e] in <09623c708fdb40a483cea147bbea7a7f>:0
exception inside UnhandledException handler: The type initializer for 'System.Windows.Forms.Screen' threw an exception.

[ERROR] FATAL UNHANDLED EXCEPTION: System.TypeInitializationException: The typeinitializer for 'System.Windows.Forms.Screen' threw an exception. ---> System.NullReferenceException: Object reference not set to an instance of an object
  at (wrapper managed-to-native) System.Windows.Forms.XplatUICarbon.CGDisplayBounds(intptr)
  at System.Windows.Forms.XplatUICarbon.get_WorkingArea () [0x00005] in <7cb6368c5ba549ff8a02965fd9de701e>:0
  at System.Windows.Forms.XplatUICarbon.get_VirtualScreen () [0x00000] in <7cb6368c5ba549ff8a02965fd9de701e>:0
  at System.Windows.Forms.XplatUI.get_VirtualScreen () [0x00000] in <7cb6368c5ba549ff8a02965fd9de701e>:0
  at System.Windows.Forms.Screen..cctor () [0x00034] in <7cb6368c5ba549ff8a02965fd9de701e>:0
   --- End of inner exception stack trace ---
  at System.Windows.Forms.MessageBox+MessageBoxForm.InitFormsSize () [0x00002] in <7cb6368c5ba549ff8a02965fd9de701e>:0
  at System.Windows.Forms.MessageBox+MessageBoxForm.RunDialog () [0x0000f] in <7cb6368c5ba549ff8a02965fd9de701e>:0
  at (wrapper remoting-invoke-with-check) System.Windows.Forms.MessageBox+MessageBoxForm.RunDialog()
  at System.Windows.Forms.MessageBox.Show (System.Windows.Forms.IWin32Window owner, System.String text, System.String caption, System.Windows.Forms.MessageBoxButtons buttons, System.Windows.Forms.MessageBoxIcon icon) [0x0000b] in <7cb6368c5ba549ff8a02965fd9de701e>:0
  at Fiddler.FiddlerApplication.DoNotifyUser (System.Windows.Forms.IWin32WindowownerWnd, System.String sMessage, System.String sTitle, System.Windows.Forms.MessageBoxIcon oIcon) [0x0002c] in <09623c708fdb40a483cea147bbea7a7f>:0
  at Fiddler.FiddlerApplication.DoNotifyUser (System.String sMessage, System.String sTitle, System.Windows.Forms.MessageBoxIcon oIcon) [0x00000] in <09623c708fdb40a483cea147bbea7a7f>:0
  at Fiddler.FiddlerApplication.ReportException (System.Exception eX, System.String sTitle, System.String sCallerMessage) [0x001a4] in <09623c708fdb40a483cea147bbea7a7f>:0
  at Fiddler.FiddlerApplication.ReportException (System.Exception ‚) [0x00006] in <09623c708fdb40a483cea147bbea7a7f>:0
  at Fiddler.frmViewer.• (System.Object, System.UnhandledExceptionEventArgs •) [0x00006] in <09623c708fdb40a483cea147bbea7a7f>:0

[Guy]

Please note that you have to run Fiddler with:

mono --arch=32 Fiddler.exe

It will won't run fluidly anyway

[Spiros]

that the error im getting when i run mono --arch=32 Fiddler.exe
“mono-sgen32” is not optimized for your Mac and needs to be updated

[Simeon]

Hello Spiros,

According to this page, Apple has stopped the support for 32-bit applications. The WinForms implementation, which Fiddler depends on, in Mono supports only 32-bit processes. As far as I know, there are no plans for Mono to support the 64-bit WinForms apps.

Fortunately, we have started to develop a new Fiddler Everywhere, which runs on .NET Core and it does not suffer from these problems. It is still in preview but it already has some basic functionality. Our current goal is to reach feature parity with the old but gold Fiddler. And as we are always listening to our customers, you could vote for your favorite features to be implemented with priority in the feedback portal.

Thanks and Regards,
Simeon
Progress Telerik