Fatal unhandled exception on startup

Operating System Details:

cat /etc/issue
Debian GNU/Linux 8 \n \l

Mono Details:

mono --version
Mono JIT compiler version 3.2.8 (Debian 3.2.8+dfsg-10)
Copyright (C) 2002-2014 Novell, Inc, Xamarin Inc and Contributors. www.mono-project.com
	TLS:           __thread
	SIGSEGV:       altstack
	Notifications: epoll
	Architecture:  amd64
	Disabled:      none
	Misc:          softdebug 
	LLVM:          supported, not enabled.
	GC:            sgen

Manager Details:

apt-cache show manager-accounting
Package: manager-accounting
Status: install ok installed
Priority: extra
Section: misc
Installed-Size: 19543
Maintainer: Lubos Hasko <lubos@luboshasko.com>
Architecture: all
Version: 17.4.79
Depends: mono-runtime, libmono-system-xaml4.0-cil, mono-devel, libgtk2.0-cil-dev, libwebkit1.1-cil
Description: Accounting software
 Manager is free accounting software for Ubuntu. It features an intuitive
 and innovative user interface with modules such as cashbook, invoicing,
 receivables, payables, taxes and comprehensive financial reports.
Description-md5: 32b8a820361f61d6e629e430297875f2
Homepage: http://www.manager.io/

Upon startup Manager fails to load with the following console message.

/opt/manager-accounting/manager-accounting 
Unhandled Exception:
System.NullReferenceException: Object reference not set to an instance of an object
  at Eto.Forms.MessageBox.Show (Eto.Forms.Control parent, System.String text, System.String caption, MessageBoxButtons buttons, MessageBoxType type, MessageBoxDefaultButton defaultButton) [0x00000] in <filename unknown>:0 
  at Eto.Forms.MessageBox.Show (Eto.Forms.Control parent, System.String text, System.String caption, MessageBoxType type) [0x00000] in <filename unknown>:0 
  at Eto.Forms.MessageBox.Show (System.String text, MessageBoxType type) [0x00000] in <filename unknown>:0 
  at ManagerDesktop.Program.Main (System.String[] args) [0x00000] in <filename unknown>:0 
[ERROR] FATAL UNHANDLED EXCEPTION: System.NullReferenceException: Object reference not set to an instance of an object
  at Eto.Forms.MessageBox.Show (Eto.Forms.Control parent, System.String text, System.String caption, MessageBoxButtons buttons, MessageBoxType type, MessageBoxDefaultButton defaultButton) [0x00000] in <filename unknown>:0 
  at Eto.Forms.MessageBox.Show (Eto.Forms.Control parent, System.String text, System.String caption, MessageBoxType type) [0x00000] in <filename unknown>:0 
  at Eto.Forms.MessageBox.Show (System.String text, MessageBoxType type) [0x00000] in <filename unknown>:0 
  at ManagerDesktop.Program.Main (System.String[] args) [0x00000] in <filename unknown>:0

Reinstalling Mono does not help.
Reinistalling Manager does not help.
Unable to roll back to previous version of Manager as there is no archive of old versions.

Please advise on how to rectify this situation.

Don’t consider this expert advice by any means. But have you updated Mono, or just reinstalled your old version. There are several threads on the forum about Mono, and your version looks old.

Possible, however it is the system default mono for Debian Jessie. I would have expected that the Ubuntu package would not have installed if the version was too old.

I currently don’t see a backport of a newer mono. I will investigate if I can feasibly update it without breaking any other mono applications on the system.

However, I would certainly appreciate if the cause of this crash could be investigated. From my point of view, the only change was Manager getting an update, and now it no longer works, but the requirements have not changed as far as I can tell.

I ended up having to upgrade entire system to the upcoming Debian 9 release.

mono --version
Mono JIT compiler version 4.6.2 (Debian 4.6.2.7+dfsg-1)
Copyright (C) 2002-2014 Novell, Inc, Xamarin Inc and Contributors. www.mono-project.com
	TLS:           __thread
	SIGSEGV:       altstack
	Notifications: epoll
	Architecture:  amd64
	Disabled:      none
	Misc:          softdebug 
	LLVM:          supported, not enabled.
	GC:            sgen

Manager appears to be working fine now.

This leads me to conclude that there is a mistake in the Debian packaging, and that the mono-runtime dependency should be versioned to prevent installation on systems that have a too old version of mono.

I just ran into the same issue on Ubuntu 14.04 LTS (Trusty) on AMD 64. I had “mono-complete” installed from Ubuntu’s default package cache. For me, the solution was accomplished by the following commands in terminal:

sudo apt-get remove mono-complete

sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF

echo "deb http://download.mono-project.com/repo/ubuntu trusty main" | sudo tee /etc/apt/sources.list.d/mono-official.list

sudo apt-get update && sudo apt-get upgrade

sudo apt-get install mono-complete

Manager now works fine, as do all my other previously-installed apps that use mono.