drop them into your Fiji.app/jars/ and remove the obsolete versions
(imagej-legacy-0.5.3.jar and scifio-0.14.2.jar) and test?
Thank you!
Johannes
P.S.: I am sorry that we're not quite there yet, but soon tests like
this will be much easier: you will only need to check an update site to
get the latest development versions, then you can test, and after that you
can uncheck the update site to get back to the stable version. But as I
said, we're not quite there yet (too busy fixing bugs such as the one you
reported).