How to Fix a Common After Effects Expression Error

It's frustrating to get a new After Effects tool, only to have it not work at all.

Unfortunately, this happens a lot with expressions in After Effects. Luckily, one of the most common After Effects expression errors is very easy to fix!

If you ever see this error:

Expression Disabled -- blah, blah, blah, something is undefined.

Expression disabled error

Try going to File > Project Settings (Command+Option+Shift+K / Ctrl+Alt+Shift+K).

Under the Expressions tab, make sure the Expression Engine is set to JavaScript.

If your expression engine is set to Legacy ExtendScript it might break your expressions.

Fix expression engine setting

Hopefully this resolves your After Effects expression errors!

Now if only After Effects would do away with Legacy ExtendScript entirely.