Android build error

For some reason when I compile my app to run in the android simulator I keep getting this error. It used to work fine and I haven't changed the app in 6 months but I have upgraded SDK. Any ideas what this means? I didn't find much helpful info on google.

/usr/local/lib/node_modules/titanium/node_modules/longjohn/dist/longjohn.js:185
        throw e;
              ^
Error: EACCES, permission denied '/opt/local/var/cores'

David