Jazz-MIDI Add-on have been updated to v.1.0.1.1
If you had an old version, it will most likely update automatically, but just for case you can manually install it.
Chrome Web Store: https://chrome.google.com/webstore/deta ... mjcbpfmbkm
Mozilla Add-ons: https://addons.mozilla.org/en-US/firefo ... jazz-midi/