After Effects Error Asked To Create Unknown Property Of Type Fix Site

This error usually happens when After Effects tries to load a project, preset, or script that references a "Pseudo Effect" or a specific property type that isn't installed on your system . 🛠️ Core Fixes

Specific Fixes Based on Common Issues:

Conclusion

Turn off layer visibility one by one to see when the error stops. Remove custom scripts from the ScriptUI Panels This error usually happens when After Effects tries

1. Open the project.
2. If you can access the timeline, press U to reveal all keyframes.
3. Look for expression errors (usually shown as a warning icon next to the expression).
4. Delete the expression or use the command: Expression Tools > Delete All Expressions (if you have a script for it).
5. If the project crashes immediately upon opening, try importing the project into a New Project (File > Import > Project) rather than opening it directly.

A surprising number of "fix" errors trace back to corrupted fonts or bad JavaScript expressions. Open the project

object

To understand the error, you must first understand how After Effects handles objects. In AE’s scripting and internal architecture, every element—a layer, a mask, an effect, a transform property (position, scale, rotation)—is an with a specific type . A surprising number of "fix" errors trace back

When working in Adobe After Effects (often when copying and pasting keyframes, using expressions, or installing third-party scripts/plugins), you receive the following error message: