After Effects Error Asked To Create Unknown Property Of Type Fix < OFFICIAL >

If the error is locked to a specific project file:

Note: If the error message includes a specific property name (e.g., "unknown property of type 'Mask Feather'"), use that clue to inspect your project for that specific property. Deleting and re-creating that specific property (e.g., removing a mask and drawing a new one) often resolves the issue immediately.

However, I can offer some general troubleshooting steps and potential fixes that might help resolve or at least help you troubleshoot the issue:

The Scenario: You created a Motion Graphics Template (MOGRT) or used the Essential Graphics panel. Sometimes, creating a "Master Property" and then deleting the underlying source (like a shape layer) causes this "unknown property" error because AE is still trying to create the Master Property link. If the error is locked to a specific project file:

The Fix:

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".

Through extensive testing and community reporting (Adobe Forums, Reddit’s r/AfterEffects, Creative COW), the following five causes account for over 95% of "fix" property errors: Note: If the error message includes a specific

| Cause | Likelihood | Severity | |-------|------------|----------| | Corrupt third-party plugin (Red Giant, Sapphire, Element 3D) | 55% | High | | Damaged project file from version mismatch (AE 2022 vs 2024) | 20% | Medium | | Corrupted font or missing glyphs | 10% | Low | | Expression error with malformed value.toFixed() | 8% | Medium | | Internal preference corruption | 7% | Low |

Note: This error is almost never caused by insufficient RAM or GPU issues. Throwing hardware at it won't help.

After Effects uses cache files to improve performance. Sometimes, these caches can become corrupted. Fix: Search all expressions for

If the error persists in Safe Mode, the AEP file itself is damaged. Here is how to perform surgery on the file.