Ensure that your After Effects software is up to date. Adobe frequently releases updates that fix known bugs and improve performance.
If you are a motion designer, video editor, or visual effects artist, you have likely encountered the dreaded cryptic red warning box in Adobe After Effects. Among the most frustrating and confusing of these is the error:
"After Effects: Asked to create unknown property of type 'fix'."
This error typically brings your workflow to a screeching halt, preventing you from saving, rendering, or even closing the application without a force quit. Unlike a simple syntax error, the "fix" property error points to deeper corruption, plugin conflicts, or project file damage. Ensure that your After Effects software is up to date
In this comprehensive 2,500+ word guide, we will break down exactly what triggers this error, why Adobe engineers named it "fix," and, most importantly, provide a step-by-step roadmap to resolve it permanently.
If the file is corrupted at the structural level (XML data corruption), you need to strip the metadata.
Prevention beats cure. Adopt these habits to never see "asked to create unknown property of type 'fix'" again. If the file is corrupted at the structural
| Prevention Tactic | Why It Works |
|------------------|---------------|
| Save as .aepx (XML-based) | XML files are human-readable and recoverable. Go to Preferences > Files and enable "Allow script to write files and network." |
| Use an Auto-Save interval of 10 minutes | Limits data loss. Set via Edit > Preferences > Auto-Save. |
| Avoid nested effects from different vendors | Mixing Boris FX with Red Giant on the same layer increases property type conflicts. |
| Collapse transformations sparingly | The "fix" error often triggers when a pre-comp with collapse transformations contains a 3D layer with a corrupt effect. |
| Update plugins before updating AE | Always update Trapcode, Sapphire, and Element 3D before upgrading your AE version. |
| Run the Built-in Project Fixer | Go to File > Scripts > Project Fixer (after installing the free script from Adobe Community). |
Try these solutions in order. Chances are, Step 1 or 2 will save your day.
If nothing else works, you might consider uninstalling and then reinstalling After Effects. Prevention beats cure
After Effects uses cache files to improve performance. Sometimes, these caches can become corrupted.
If the error specifically says "unknown property of type 'Pseudo/...'": You are missing a plugin or script that creates custom UI controls. Install the specific plugin required by that project file.