User Guide Cancel

Expression errors

  1. After Effects User Guide
  2. Beta releases
    1. Beta Program Overview
    2. After Effects Beta Home
  3. Getting started
    1. Get started with After Effects
    2. What's new in After Effects 
    3. Release Notes | After Effects
    4. After Effects system requirements
    5. Keyboard shortcuts in After Effects
    6. Supported File formats | After Effects
    7. Hardware recommendations
    8. After Effects for Apple silicon
    9. Planning and setup
  4. Workspaces
    1. General user interface items
    2. Get to know After Effects interface
    3. Workflows
    4. Workspaces, panels, and viewers
  5. Projects and compositions
    1. Projects
    2. Composition basics
    3. Precomposing, nesting, and pre-rendering
    4. View detailed performance information with the Composition Profiler
    5. CINEMA 4D Composition Renderer
  6. Importing footage
    1. Preparing and importing still images
    2. Importing from After Effects and Adobe Premiere Pro
    3. Importing and interpreting video and audio
    4. Preparing and importing 3D image files
    5. Importing and interpreting footage items
    6. Working with footage items
    7. Detect edit points using Scene Edit Detection
    8. XMP metadata
  7. Text and Graphics
    1. Text
      1. Formatting characters and the Character panel
      2. Text effects
      3. Creating and editing text layers
      4. Formatting paragraphs and the Paragraph panel
      5. Extruding text and shape layers
      6. Animating text
      7. Examples and resources for text animation
      8. Live Text Templates
    2. Motion Graphics
      1. Work with Motion Graphics templates in After Effects
      2. Use expressions to create drop-down lists in Motion Graphics templates
      3. Work with Essential Properties to create Motion Graphics templates
      4. Replace images and videos in Motion Graphics templates and Essential Properties
      5. Animate faster and easier using the Properties panel
  8. Drawing, Painting, and Paths
    1. Overview of shape layers, paths, and vector graphics
    2. Paint tools: Brush, Clone Stamp, and Eraser
    3. Taper shape strokes
    4. Shape attributes, paint operations, and path operations for shape layers
    5. Use Offset Paths shape effect to alter shapes
    6. Creating shapes
    7. Create masks
    8. Remove objects from your videos with the Content-Aware Fill panel
    9. Roto Brush and Refine Matte
  9. Layers, Markers, and Camera
    1. Selecting and arranging layers
    2. Blending modes and layer styles
    3. 3D layers
    4. Layer properties
    5. Creating layers
    6. Managing layers
    7. Layer markers and composition markers
    8. Cameras, lights, and points of interest
  10. Animation, Keyframes, Motion Tracking, and Keying
    1. Animation
      1. Animation basics
      2. Animating with Puppet tools
      3. Managing and animating shape paths and masks
      4. Animating Sketch and Capture shapes using After Effects
      5. Assorted animation tools
      6. Work with Data-driven animation
    2. Keyframe
      1. Keyframe interpolation
      2. Setting, selecting, and deleting keyframes
      3. Editing, moving, and copying keyframes
    3. Motion tracking
      1. Tracking and stabilizing motion
      2. Face Tracking
      3. Mask Tracking
      4. Mask Reference
      5. Speed
      6. Time-stretching and time-remapping
      7. Timecode and time display units
    4. Keying
      1. Keying
      2. Keying effects
  11. Transparency and Compositing
    1. Compositing and transparency overview and resources
    2. Alpha channels and masks
    3. Track Mattes and Traveling Mattes
  12. Adjusting color
    1. Color basics
    2. Color management
    3. Color Correction effects
    4. OpenColorIO and ACES color management
  13. Effects and Animation Presets
    1. Effects and animation presets overview
    2. Effect list
    3. Effect Manager
    4. Simulation effects
    5. Stylize effects
    6. Audio effects
    7. Distort effects
    8. Perspective effects
    9. Channel effects
    10. Generate effects
    11. Transition effects
    12. The Rolling Shutter Repair effect
    13. Blur and Sharpen effects
    14. 3D Channel effects
    15. Utility effects
    16. Matte effects
    17. Noise and Grain effects
    18. Detail-preserving Upscale effect
    19. Obsolete effects
  14. Expressions and Automation
    1. Expressions
      1. Expression basics
      2. Understanding the expression language
      3. Using expression controls
      4. Syntax differences between the JavaScript and Legacy ExtendScript expression engines
      5. Editing expressions
      6. Expression errors
      7. Using the Expressions editor
      8. Use expressions to edit and access text properties
      9. Expression language reference
      10. Expression examples
    2. Automation
      1. Automation
      2. Scripts
  15. Immersive video, VR, and 3D
    1. Construct VR environments in After Effects
    2. Apply immersive video effects
    3. Compositing tools for VR/360 videos
    4. Advanced 3D Renderer
    5. Import and add 3D models to your composition
    6. Import 3D models from Creative Cloud Libraries
    7. Image-Based Lighting
    8. Extract and animate lights and cameras from 3D models
    9. Tracking 3D camera movement
    10. Cast and accept shadows
    11. Work in 3D Design Space
    12. 3D Transform Gizmos
    13. Do more with 3D animation
    14. Preview changes to 3D designs real time with the Mercury 3D engine
    15. Add responsive design to your graphics 
  16. Views and Previews
    1. Previewing
    2. Video preview with Mercury Transmit
    3. Modifying and using views
  17. Rendering and Exporting
    1. Basics of rendering and exporting
    2. H.264 Encoding in After Effects
    3. Export an After Effects project as an Adobe Premiere Pro project
    4. Converting movies
    5. Multi-frame rendering
    6. Automated rendering and network rendering
    7. Rendering and exporting still images and still-image sequences
    8. Using the GoPro CineForm codec in After Effects
  18. Working with other applications
    1. Dynamic Link and After Effects
    2. Working with After Effects and other applications
    3. Sync Settings in After Effects
    4. Creative Cloud Libraries in After Effects
    5. Plug-ins
    6. Cinema 4D and Cineware
  19. Collaboration: Frame.io, and Team Projects
    1. Collaboration in Premiere Pro and After Effects
    2. Frame.io
      1. Install and activate Frame.io
      2. Use Frame.io with Premiere Pro and After Effects
      3. Frequently asked questions
    3. Team Projects
      1. Get Started with Team Projects
      2. Create a Team Project
      3. Collaborate with Team Projects
  20. Memory, storage, performance
    1. Memory and storage
    2. How After Effects handles low memory issues while previewing    
    3. Improve performance
    4. Preferences
    5. GPU and GPU driver requirements for After Effects
  21. Knowledge Base
    1. Known issues
    2. Fixed issues
    3. Frequently asked questions
    4. After Effects and macOS Ventura
    5. How After Effects handles low memory issues while previewing

When an expression fails to evaluate, expression errors appear in a warning banner at the bottom of the Composition and Layer panels. After Effects does not disable the expression but continues to evaluate it. The warning banner is displayed as long as the expression fails to evaluate; that is, until the expression is either fixed or manually disabled.

The expression error UI

Here’s an example of what the expression error warning banner looks like:

An example expression error
An example expression error

A. Left or Right arrow buttons B. The Reveal Expression C. The Expand/Collapse Warning 

  • The Left or Right arrow buttons display the previous or next expression error when multiple expressions fail to evaluate.
  • The Reveal Expression (magnifying glass) button exposes the property with the failing expression in the Timeline panel. If the expression is in a different composition, that composition opens.
  • The Expand/Collapse Warning (up/down arrows) button shows or hides the error text.

The expression error text is one line only, and is clipped to the width of the Composition panel.

To see the full expression error text

Click  next to the expression. The complete error appears in a dialog box.

Expression error dialog box
Expression error dialog box

To hide the warning banner

hide warning banner

Choose After Effects > Preferences > Scripting & Expressions (macOS) or Edit > Preferences > General (Windows) and disable Show Warning Banner When Project Contains Expressions Errors.

When this option is disabled, the warning banner remains hidden even when new expression errors occur.

Re-enable this option to view expression errors.

Reveal expression errors

If an expression cannot be processed, After Effects displays a message explaining the error and automatically disables the expression. A yellow warning icon appears next to the expression. Click the warning icon to view the error message again.

To show expressions that have errors, select one or more layers. Right-click (Windows) or Control-click (macOS) a selected layer in the Timeline panel. Choose Reveal Expression Errors from the context menu.

Some expressions rely on the names of layers or properties in your project. If you change the name of a layer or property that is involved in an expression, After Effects attempts to update the expression to use the new name. However, in some complex cases, After Effects is unable to automatically update the expression. In this case, the expression may produce an error message and you must update the expression yourself.

Note:

The expression may not work if you are running After Effects in a different language, or if you changed the names of the items (such as layers, effects, or other property groups). To enable the expression, modify the expression to use the new names or the strings that match the language in which you are running After Effects.

The examples in this document were created for the default state of After Effects running in English. Some examples in this document will not work without such modification.

Errors caused by precomposing layers

Precomposing multiple layers can cause expressions that refer to a property of one of the layers to produce an error. You have to update these expressions to refer to the layer within the new composition. This is especially a concern with expressions that use thisComp instead of referring to a composition by its name. (See About precomposing and nesting.)

Note:

The arguments for some effects in After Effects have changed from the arguments in previous versions. If you have existing expressions that use argument index references instead of argument names, update the expressions to use argument names.

More Expression resources

Now that you have understood some of the concepts behind expressions, come to the community for some real-life examples, and to share your work.

You can also check out Dan Ebberts' excellent collection of example expressions and tutorials on his MotionScript website.

The AE Enhancers forum also provides many examples and much information about expressions, as well as scripts and animation presets.

 Adobe

Get help faster and easier

New user?