monodevelop stopped working

I had a working project, including the use of monodevelop directly from within Unity.

Today, when I tried to edit a script, I get this error (consistently):
System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index
at System.ThrowHelper.ThrowArgumentOutOfRangeException () [0x00000] in :0
at System.Collections.Generic.List1[MonoDevelop.Ide.Gui.IDockNotebookTab].get_Item (Int32 index) [0x00000] in <filename unknown>:0
at MonoDevelop.Ide.Gui.DockNotebook.RemoveTab (Int32 page, Boolean animate) [0x00000] in /home/builduser/buildslave/monodevelop/build/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Gui/DockNotebook.cs:215
at MonoDevelop.Ide.Gui.DefaultWorkbench.RemoveTab (Int32 pageNum, Boolean animate) [0x0000e] in /home/builduser/buildslave/monodevelop/build/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Gui/DefaultWorkbench.cs:1194
at MonoDevelop.Ide.Gui.SdiWorkspaceWindow.CloseWindow (Boolean force, Boolean animate) [0x00032] in /home/builduser/buildslave/monodevelop/build/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Gui/SdiWorkspaceWindow.cs:387
at MonoDevelop.Ide.Gui.Document.Close () [0x00000] in /home/builduser/buildslave/monodevelop/build/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Gui/Document.cs:492
at MonoDevelop.Ide.RootWorkspace.Close (Boolean saveWorkspacePreferencies, Boolean closeProjectFiles) [0x00091] in /home/builduser/buildslave/monodevelop/build/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide/RootWorkspace.cs:456
at MonoDevelop.Ide.RootWorkspace.Close (Boolean saveWorkspacePreferencies) [0x00000] in /home/builduser/buildslave/monodevelop/build/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide/RootWorkspace.cs:438
at MonoDevelop.Ide.RootWorkspace.Close () [0x00000] in /home/builduser/buildslave/monodevelop/build/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide/RootWorkspace.cs:433
at MonoDevelop.Ide.RootWorkspace.OpenWorkspaceItem (System.String filename, Boolean closeCurrent, Boolean loadPreferences) [0x00021] in /home/builduser/buildslave/monodevelop/build/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide/RootWorkspace.cs:523
at MonoDevelop.Ide.RootWorkspace.OpenWorkspaceItem (System.String filename, Boolean closeCurrent) [0x00000] in /home/builduser/buildslave/monodevelop/build/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide/RootWorkspace.cs:517
at MonoDevelop.Ide.RootWorkspace.OpenWorkspaceItem (System.String filename) [0x00000] in /home/builduser/buildslave/monodevelop/build/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide/RootWorkspace.cs:512
at MonoDevelop.Ide.IdeApp.OpenFiles (IEnumerable
1 files) [0x00142] in /home/builduser/buildslave/monodevelop/build/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide/Ide.cs:388

I've tried restarting Unity, forcing that solution file to be rebuilt, etc, all with no success.

Interestingly, I copied this project (*.sln files and all) to my MacOS box and it works just fine. I also tried running monodevelop directly on my Linux desktop, loading the same solution file and it also works. For now, this is
a workaround but it would be nice to get to the bottom of this. I'll attach the "broken" solution file, but it only seems to affect the internal monodevelop-Unity

[quote=“Gary_Thomas128”, post:1, topic: 598075]
I had a working project, including the use of monodevelop directly from within Unity.

Today, when I tried to edit a script, I get this error (consistently):
System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index
at System.ThrowHelper.ThrowArgumentOutOfRangeException () [0x00000] in :0
at System.Collections.Generic.List1[MonoDevelop.Ide.Gui.IDockNotebookTab].get_Item (Int32 index) [0x00000] in <filename unknown>:0 at MonoDevelop.Ide.Gui.DockNotebook.RemoveTab (Int32 page, Boolean animate) [0x00000] in /home/builduser/buildslave/monodevelop/build/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Gui/DockNotebook.cs:215 at MonoDevelop.Ide.Gui.DefaultWorkbench.RemoveTab (Int32 pageNum, Boolean animate) [0x0000e] in /home/builduser/buildslave/monodevelop/build/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Gui/DefaultWorkbench.cs:1194 at MonoDevelop.Ide.Gui.SdiWorkspaceWindow.CloseWindow (Boolean force, Boolean animate) [0x00032] in /home/builduser/buildslave/monodevelop/build/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Gui/SdiWorkspaceWindow.cs:387 at MonoDevelop.Ide.Gui.Document.Close () [0x00000] in /home/builduser/buildslave/monodevelop/build/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Gui/Document.cs:492 at MonoDevelop.Ide.RootWorkspace.Close (Boolean saveWorkspacePreferencies, Boolean closeProjectFiles) [0x00091] in /home/builduser/buildslave/monodevelop/build/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide/RootWorkspace.cs:456 at MonoDevelop.Ide.RootWorkspace.Close (Boolean saveWorkspacePreferencies) [0x00000] in /home/builduser/buildslave/monodevelop/build/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide/RootWorkspace.cs:438 at MonoDevelop.Ide.RootWorkspace.Close () [0x00000] in /home/builduser/buildslave/monodevelop/build/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide/RootWorkspace.cs:433 at MonoDevelop.Ide.RootWorkspace.OpenWorkspaceItem (System.String filename, Boolean closeCurrent, Boolean loadPreferences) [0x00021] in /home/builduser/buildslave/monodevelop/build/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide/RootWorkspace.cs:523 at MonoDevelop.Ide.RootWorkspace.OpenWorkspaceItem (System.String filename, Boolean closeCurrent) [0x00000] in /home/builduser/buildslave/monodevelop/build/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide/RootWorkspace.cs:517 at MonoDevelop.Ide.RootWorkspace.OpenWorkspaceItem (System.String filename) [0x00000] in /home/builduser/buildslave/monodevelop/build/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide/RootWorkspace.cs:512 at MonoDevelop.Ide.IdeApp.OpenFiles (IEnumerable1 files) [0x00142] in /home/builduser/buildslave/monodevelop/build/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide/Ide.cs:388

I’ve tried restarting Unity, forcing that solution file to be rebuilt, etc, all with no success.

Interestingly, I copied this project (*.sln files and all) to my MacOS box and it works just fine. I also tried running monodevelop directly on my Linux desktop, loading the same solution file and it also works. For now, this is
a workaround but it would be nice to get to the bottom of this. I’ll attach the “broken” solution file, but it only seems to affect the internal monodevelop-Unity
[/quote]

BTW, this is now happening on all of my projects, so something major seems to have changed. I’m sure I used monodevelop since I updated to the latest version (2015-09-15), so it’s not clear what might have changed.