Im having some trouble opening an older .fla file, could use some help

A buddy of mine got me into the madness combat series a while back, and i originally started work on one of my own animations, but i ended up stopped due to not having enough free time. now its been a while, and i have a newer version of adobe animate but when i try to open the files it tells me that there was an error when opening the file, the files are very old like 2011 old but they worked fine a while ago, any help would be much appreciated.