It looks like you're using Ruby 2.3. OpenStudio 1.13 is currently compatible with Ruby 2.0 (link).

Try uninstalling 2.3 and installing 2.0 using the Optional - Install Ruby instructions.

It looks like you're using Ruby 2.3. OpenStudio 1.13 is currently compatible with Ruby 2.0 (link).

Try uninstalling 2.3 and installing 2.0 using the Optional - Install Ruby instructions.

It looks like you're using Ruby 2.3. OpenStudio 1.13 is currently compatible with Ruby 2.0 (link).

Try uninstalling 2.3 and installing 2.0 using the Optional - Install Ruby instructions.