The assembly mscorlib.dll was not found or could not be loaded
.net, mono, mscorlib, xbuild
Solution
I figured it out - I needed to set MONO_PATH to:
`/opt/my-app/mono/lib/mono/4.0:/opt/my-app/mono/lib/mono/3.5:/opt/my-app/mono/lib/mono/2.0:.`
So I needed to tell it where to look for libraries; I had (wrongly) assumed that would be automatic based on the location of the mono executable.
Problem
Firstly, I've seen this question, and while the problem seems similar, it is not the same. I'm running a trimmed down mono, built without the 4.5 profile using `./configure --with-profile4=yes --with-profile4_5=no`. I have an application that targets .NET 4.0, built using mono's `xbuild`. When I run it against my trimmed down mono installation, I get this error: ` The assembly mscorlib.dll was not found or could not be loaded. It should have been installed in the `/opt/my-app/mono/lib/mono/4.5/mscorlib.dll' directory. ` Now, I'm not referencing only 4.0 assemblies - nothing from 4.5, AFAICS. Why might I be getting this error? I'm not sure if it's related, but I get this warning when building with `xbuild` (but not when building with `msbuild`, although I still get the `mscorlib.dll` when running against my trimmed down mono): ``` warning CS1685: The predefined type `System.Runtime.CompilerServices.ExtensionAttribute' is defined multiple times. Using definition from `mscorlib.dll' ``` I'm also not sure if this is relevant either, but the build machine does has .NET 4.5 installed.