Apply
Apply is the commit. It resolves your variables, creates whatever effect controls the expression declares, sets the expression, and reports what actually happened — as one atomic operation that a single Cmd+Z in After Effects undoes completely.
Apply writes to your Apply target: the active tab's pinned property if it has one, otherwise whatever is selected in AE.
What Apply does, in order
- Resolves every
{{name}}variable — from its authored default when applying straight from a Library row, or from the active session's wiring when applying from the editor, excluding any variable that's being delivered as a control instead. - Creates any declared effect controls on the target layer, auto-resolving name collisions (AE may rename on conflict). When a Variables session is set to delivery Pseudo effect, it generates and applies one pseudo effect instead — see Pseudo Effect Authoring.
- Sets the expression.
- Reports AE's real verdict and exactly which controls were actually created.
Step 4 is deliberately specific. "Applied successfully" would be a weaker claim than a list naming each control that now exists on the layer, and the list is what you get.
One Apply: the controls the expression needed, created on the layer, and the expression set — undone together by a single Cmd+Z.
One undo in After Effects
The whole operation is undo-grouped. A single Cmd+Z in After Effects undoes the entire thing — the controls and the expression together, not one at a time.
This is the behavior you want when an apply turns out to be wrong: you press undo once and the layer is as it was, with no orphaned sliders left behind to clean up by hand.
If a step fails
Failure is unwound rather than left half-done. If any step fails:
- every control created so far is removed,
- the original expression is restored exactly,
- and the restoration is verified before anything is reported to you.
The verify-before-report ordering is the same principle Audition is built on. A rollback you're told about but that didn't actually happen would be the worst possible outcome, so the report waits on the confirmation.
Applying to several properties at once
If more than one expression-capable property is selected in AE when you click Apply, it fans out to every selected property in a single undo group. Check the selected properties before applying: the toolbar action applies to the current selection unless the active tab has a pinned target.
On completion, a per-target list shows each property as applied or failed, carrying AE's own error for any that failed. A partial success is reported as exactly that — you see which targets took the expression and which didn't, rather than one summary verdict averaging over both.
A single-property selection behaves exactly as described in the sections above.
Where to reach Apply
- A row's Apply action in the Library.
- Cmd/Ctrl+Enter or the Apply button on the toolbar in the editor. The toolbar action is disabled, with an explaining tooltip, when the editor is empty or there's no valid target. Check the status bar for the active pin.
- The Compact insert panel.
An expression applies identically whichever surface you launched it from — and the IDE refuses to apply rather than emitting an unresolvable placeholder. The full treatment of that rule lives on What Happens at Apply.
Settings carries an Applying section governing how much checking happens before controls are created and the expression is set. It's kept separate from Diagnostics on purpose: it governs Apply's own gate, not the editor's live squiggles. See Settings, Section by Section.