After Effects Error Asked To Create Unknown Property Of Type Fix [better]

This error message, "After Effects error: asked to create unknown property of type...," is one of the most cryptic and frustrating crashes in After Effects. It essentially means the software tried to generate a parameter (like a position keyframe, a mask, or an effect controller) but the internal "blueprint" for that parameter was missing or corrupted.

Because this error is triggered by different underlying causes, there is no single "fix." Instead, you have to systematically rule out the common culprits.

Here is a deep dive into why this happens and how to fix it.

---

11. Final Checklist

Before reopening After Effects after encountering the error, run through this checklist:

• [ ] Did you force quit AE properly (not just close the window)?
• [ ] Have you purged all memory and disk cache?
• [ ] Did you test the project in Safe Mode (third-party plugins disabled)?
• [ ] Did you rename your MediaCore folder to isolate plugins?
• [ ] Did you replace all missing fonts?
• [ ] Did you search expressions for .toFixed(?
• [ ] Did you try importing the damaged AEP as a composition into a fresh project?
• [ ] Did you try opening the project in an older AE version?
• [ ] Do you have a backup from before the error first appeared?

---

Step 3: The "Master Property" Check (For Essential Graphics/MOGRTs)

If you are working with a Motion Graphics template (.mogrt) from Envato or Adobe Stock:

• Go to the Essential Graphics panel.
• Look for any "Master Properties" that are broken (they may show an error icon or blank value).
• Delete and re-add those specific master properties. The original template likely used an old data type that your version of AE doesn't recognize.

Specific Fixes Based on Common Issues:

• "Unknown Property" Error: This can sometimes occur due to expressions or scripts trying to access properties that no longer exist or have been renamed. Review any expressions or scripts in your project.

• Effect Presets and Third-Party Plugins: Ensure that any third-party plugins or effect presets you're using are compatible with your version of After Effects.

If you're still having trouble, providing more details about your error message and the steps leading up to it could help narrow down a more specific solution.

The "asked to create unknown property of type" error in Adobe After Effects typically occurs when the software encounters a pseudo-effect, preset, or third-party plugin that it cannot properly recognize or that has conflicting naming conventions. Primary Fixes This error message, "After Effects error: asked to

Rename Pseudo-Effect Items: If you are creating or using custom pseudo-effects, ensure none of the items use names that conflict with After Effects' internal structure (e.g., avoid naming a parameter "Layer").

Update Legacy Expressions: Go to File > Scripts > Update Legacy Expressions.jsx. This can resolve issues where projects from older versions of After Effects use syntax that is no longer supported in the current JavaScript engine.

Identify and Remove Scripts: Faulty or outdated scripts in your ScriptUI Panels folder can trigger this error on startup.

Windows: C:\Program Files\Adobe\Adobe After Effects (version)\Support Files\Scripts\ScriptUI Panels

macOS: /Applications/Adobe After Effects (version)/Scripts/ScriptUI Panels

Try removing all scripts and re-adding them one by one to find the culprit.

Check Third-Party Plugins: Verify that all required plugins for your project (e.g., Boris FX Continuum, Red Giant Universe, or Sapphire) are correctly installed and updated. If a project was created on a machine with a plugin you don't have, After Effects may throw this error. Project Troubleshooting asked to create unknown property of type - Adobe Community

This error typically occurs when After Effects encounters a pseudo-effect (custom effect controls) or a Master Property [ ] Did you force quit AE properly

it does not recognize, often due to a mismatch between software versions, missing plugins, or conflicting font/layer names Immediate Fixes Update Legacy Expressions: File > Scripts > Update Legacy Expressions

. This can resolve errors caused by older project files using outdated JavaScript syntax. Check for Missing Plugins:

Ensure any third-party plugins (like Boris FX or Mt. Mograph) used in the project are installed and up-to-date. Rename Problematic Items: Avoid using system-reserved words like "Menu Type"

in custom pseudo-effects or Master Properties, as these can cause structural conflicts. Advanced Troubleshooting Isolate the Culprit:

Turn off layer visibility one by one to see when the error stops. Remove custom scripts from the ScriptUI Panels

folder (found in the AE installation directory) and add them back one at a time to find the "troublemaker". Clear User Presets: Navigate to ~/Documents/Adobe/After Effects [Version]/User Presets

and temporarily move the contents elsewhere. Corrupted variations of plugins can trigger this dialogue. Fix Font Conflicts: Unsync and resync Adobe Fonts

or reinstall third-party fonts used in the project, especially if they are variable fonts. Reset Preferences: Launch After Effects while holding Ctrl+Alt+Shift (Windows) or Command+Option+Shift (Mac) to delete the preferences file. Import into a New Project: Create a brand new file and use File > Import > File move to Step 2.

to bring your existing project into it. This often bypasses corrupted project settings. Are you seeing this error at startup or when clicking a specific layer in an existing project? asked to create unknown property of type - Adobe Community

---

Technique C: The "AEP to AET" Conversion

• Open the damaged project.
• Immediately go to File > Export > Save as XML (if available – hidden by default, enable via preferences).
• Alternatively, save as an AET (After Effects Template). Templates handle corruption more gracefully.

---

Solution 3: Purge All Memory & Disk Cache

Sometimes cached frames or internal data structures cause property conflicts.

1. Open After Effects.
2. Go to Edit > Purge > All Memory & Disk Cache.
3. Restart the application.

Expression Troubleshooting:

The .toFixed() method in expressions can confuse After Effects when fed non-numeric values.

Bad expression that can cause "fix":

// This can trigger the error if x is undefined:
x = thisComp.layer("Null").effect("Slider")("Slider");
x.toFixed("fix"); // Incorrect usage

Fix:
Search all expressions for .toFixed( and ensure the argument is a number. Replace toFixed("fix") with toFixed(2).

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

---

Step 1: The "Shut Up" Fix (Clear the Error)

Sometimes this is just a playback hiccup.

• Clear the cache: Go to Edit > Purge > All Memory & Disk Cache.
• Restart AE: Close the program completely and reopen the project.
• Try again. If the error comes back immediately, move to Step 2.