If you’re like me, you took no notice when Adobe updated After Effects’s expression engine. This isn’t about the change in the expression field, where different components of your expression are represented by different color text as well as some other changes. This is about an update from ExtendScript, based on ECMASCript 3 (1999), to ECMAScript 2018 which occurred with the release of After Effects 16.0 (2020). You would expect such a long chasm between updates would cause some problems with scripts written before the change, and the answer to that, like so many things in life, is: it depends.
Any scripts crashing that weren’t before?
Basically in short, After Effects added a new expression engine… but didn’t really announce it and what that means. It means you get faster and better expressions but they are not cross compatible with the older version expression engine and thus you have to switch between them.
Support Ticket, AE Scripts + Plugins, Sam, 6 Feb 2020
If this happens to you, the cure is simple.
Write expressions and want to know more?