When something misbehaves
Symptom-side guide to the issues we see most. For the per-code lookup, jump to the Error codes reference.
Panel is blank or shows "CSInterface unavailable"
NO_CEPThe panel renders empty or surfaces a NO_CEP error. This only happens when Sidekick is running outside AE, or when the bundled CEP shim failed to load.
Production users should never see this. If you do, the install is corrupt. Reinstall the latest .zxp and reopen AE. If it persists, file a bug with the AE version and OS.
"ExtendScript returned undefined"
UNDEFINEDSidekick made an internal call to AE that came back as the literal string undefined. The jsx host is not loaded.
Reopen AE. The panel re-loads its jsx host on mount. If reopening does not clear it, reinstall the .zxp.
"ExtendScript engine error"
EVAL_ERRORAE's ExtendScript interpreter threw while running a generated expression or script. Common causes are a typo in a generated app.beginUndoGroup block, or a property reference that disappeared between Send and Apply.
Click the response's Details toggle to see the full ExtendScript message. If the expression looks reasonable, retry once. If the property has been deleted or moved, refresh your selection and resubmit.
"ExtendScript returned empty response"
EMPTYThe CEP bridge fired with an empty payload. This is almost always transient: AE's CEP runtime can drop characters during fast typing.
Retry once. If it recurs every time, file a bug.
Gemini returns a blank response
With Gemini 2.5 thinking models, long prompts can burn the entire maxOutputTokens budget on internal reasoning, leaving nothing for the actual answer. Sidekick will tell you finishReason: MAX_TOKENS.
Switch your Gemini model in Settings to gemini-2.5-flash or gemini-2.5-flash-lite (non-thinking variants). They return faster and finish within the budget.
OpenAI returns HTTP 400 on a structured response
HTTP_400OpenAI's strict json_schema mode rejected the request. This usually means the schema picked up a feature strict mode does not allow.
Switch to Anthropic temporarily – its tool-use structured output does not have the same strict-mode constraint. File a bug with your prompt so we can tighten the schema.
Multi-target Apply opens N undo groups
After applying an expression to many properties at once, undoing requires one Cmd or Ctrl-Z per property.
This is a known follow-up. Workaround: undo N times. A batched-undo fix is on the roadmap.
Context is not refreshing while I iterate
You changed your selection in the timeline but Sidekick keeps using the old context.
You probably pinned the selection earlier. Click the ✕ on the pinned chip in the chat header to unpin and let Sidekick re-read your live selection.
Toolbar's "Open Helper" button does nothing, or I cannot close the chat
Open works fine for some users but not others. Close from the Toolbar never works.
The only reliable way to dismiss the chat panel is AE's native panel × button at the top of the panel, or right-click the panel tab and choose Close Panel. Three previous attempts at programmatic close all crashed AE, so this is intentional.
If Open from the Toolbar is not working, check that the chat panel is registered under Window > Extensions. If it is missing, fully quit and reopen AE.
I installed the .zxp but the panels do not appear
After dragging onto the ZXP installer, you cannot see Sidekick under Window > Extensions.
AE caches the CEP bundle list at startup. Fully quit AE (not just close the project) and reopen. The panels register on the next launch.