You've misdiagnosed the problem. The issue isn't the internal message is too long, it's that you've displayed the MException object err instead of the error message in your catch block. Try something like
...
catch err;
disp(err.identifier)
disp(err.message)
end;
I'd also suggest at least mildly that if this is a real problem your directory nesting is too deep or you're using excessively long file/subdirectory naming conventions, or both...Used to be the Winders OS filelength limit was 255 chars iirc and the above is getting dangerously close methinks plus it's a terrible nuisance albeit I understand these have to have been machine-generated.
