After Effects Error Asked To Create Unknown Property Of Type Fix

Use binary search in a copy of your project:

In many reported cases, the “FIX” property comes from broken automation scripts (e.g., old version of Motion 2, DuIK, or TextEvo). Temporarily removing those from ScriptUI Panels folder solves the issue. Use binary search in a copy of your project:

Sometimes, a simple restart can resolve the issue. Close After Effects, wait a few seconds, and then reopen it. In many reported cases, the “FIX” property comes

The Scenario: You have an expression (the little pick-whip code) linking one property to another. Sometimes, if the source property is deleted or renamed, the expression tries to "create" a link to a property that no longer exists, confusing AE. Sometimes, a simple restart can resolve the issue

The Fix: