Back in 2012/2013 I've imported a stack of home video tapes from my DV camera into iMovie. I also converted a lot of files created by earlier versions of iMovie, some of them dating back as far as 2003 or thereabouts.
For as much as 2 years I haven't touched iMovie or those files. What I did do was update my OSX and all my apps along with it, including iMovie. I'm now on El Capitan (wish I Kept Yosemite) and my iMovie cannot read the iMovie files dating from 2012/13.
Any thoughts? Tools?