I was having the exception:
Unable to cast transparent proxy to type 'Roslyn.Utilities.SerializableDataStorage'. Unable to cast transparent proxy to type 'Roslyn.Utilities.SerializableDataStorage'.
... when I opened an solution file with:
Since this command was working fine before (and I don't think there is an dependency of VisualStudio), I knew that something weird was going on.
It turned out that there was a Roslyn.Services.dll started which used the previous version (hence the remoting serialization problem), and after stopping this process, the script was working again
(btw, I don't think that that the new version starts this process (unless it does it very fast)) Update: the Roslyn.Services.dll process is also used in the latest version. The issue is that I was compiling the O2 Platform to target x86 while I'm on a 64bit machine (for now the solution is to use 'Any CPU' as the platform target)
Here is a document with some screenshots on what was going on and the before and after errors:
1) Using Roslyn (first tests).pdf