Sometimes, the problem isn't with your project at all, but with After Effects itself. Corrupted workspace or preference files can cause all sorts of strange behavior, including errors when reading property types.

To check all expressions at once: Edit > Find → Search for toFixed( → Check the box .

If the error explicitly references a missing effect or third-party plug-in framework (such as Red Giant or Boris FX Continuum), the data fields cannot map correctly.

If you're seeing this pop-up, After Effects is basically looking for a "Pseudo Effect" or a specific plugin parameter it can't find. Here’s how to clear it:

To fix the problem effectively, it's crucial to understand its root cause. Based on user reports and community discussions, this error usually stems from one of the following issues.

Ensure all layers and effects referenced in your code match their current names exactly.

: Missing or un-updated third-party plug-ins like Magic Bullet Looks or Video Copilot's Saber.

to bring your old project into it. This can sometimes bypass project-level corruption. Change Expression Engine File > Project Settings > Expressions , try switching the "Expressions Engine" to Legacy ExtendScript Error: asked to created unknown property of type "x" (1d16)

C:\Program Files\Adobe\Adobe After Effects (Your Version)\Support Files\Scripts\ScriptUI Panels

Ensure that your After Effects software is up to date. Adobe frequently releases updates that fix known bugs and improve performance.

Ensure your computer meets the minimum system requirements for After Effects. Also, make sure your graphics drivers are up to date, as outdated drivers can cause issues.