Mono on MacOSX - “The runtime version supported by this application is unavailable.” v4.5

Question

I have just installed Mono v4.0.4 on MACOSX 10.10.5 Yosemite. The installer package was: MonoFramework-MDK-4.0.4.4.macos10.xamarin.x86.pkg downloaded from http

Answer 1

mono --runtime=

That option is to control the CLR runtime:

CLR version .NET version
1.0         1.0
1.1         1.1
2.0         2.0, 3.0, 3.5
4           4, 4.5, 4.6

If you disasm xsp4.exe you will see that it requires a host that can provide the CLR 4.0 runtime:

ikdasm xsp4.exe | head -n 2

// Metadata version: v4.0.30319

Or via xCorFlags:

>>corflags xsp4.exe

Mono/.NET Framework CorFlags Conversion Tool.  Version  1.0.5643.36015
Copyright (c) SushiHangover.  All rights reserved.

Version   : v4.0.30319
CLR Header: 2.5
PE        : PE32
CorFlags  : 0x9
ILONLY    : 1
32BITREQ  : 0
32BITPREF : 0
Signed    : 1

Mono will auto-detect the runtime required by probing the CIL that it is loading, so there is no need to specify it unless you really need to force a different runtime version.

FYI: Mono installs shell scripts for tools/utilities for xsp4 (and others) so you do not have to hand-type the paths:

cat `which xsp4`

#!/bin/sh
exec /Library/Frameworks/Mono.framework/Versions/4.2.1/bin/mono $MONO_OPTIONS "/Library/Frameworks/Mono.framework/Versions/4.2.1/lib/mono/4.5/xsp4.exe" "$@"