Reason 6.5.3 and Reason Essentials 1.5.3 fix a few serious bugs, the most important being a problem where the program could crash under Mac OS X 10.8. There are no new features added. These new versions have replaced versions 6.5 and 1.5 of Reason and Reason Essentials. It is recommended that you upgrade as soon as is convenient. Click here for a full fix list.