How to downgrade mono 4.2.1 to 3.12?

Question

Mono 4.2.1 simply has way too many glitches. I tried using the steps in the answers of this question, but when I type mono --version, I get:

Mono JIT compiler version 4.2.1 (Debian 4.2.1.102+dfsg2-7ubuntu4).

I want mono 3.12, and I have no idea how to do this.

Solution

I found the answer provided here --- as painstaking as it was --- the only viable solution.

My code to run for anyone wishing to downgrade to mono V3.12 that would like to avoid navigating dependencies hell...

$ mono -V
Mono JIT compiler version 3.12.1 (tarball Fri Mar  6 19:12:47 UTC 2015)
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

Comments

[QwertyChouskie]

You could try upgrading first (mono-project.com/download/#download-lin), 4.2.1 is an old version.

[Big Ben GamerGuyKSPMC]

Thank you, but I want 3.12

[sempaiscuba]

It would be better to include the main steps (and a description of the code) here in your answer in case the URLs change.