> For the complete documentation index, see [llms.txt](https://help.littledata.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.littledata.io/event-editor/event-customiser-faq.md).

# FAQ and troubleshooting

### General

**Do changes affect historical data?** No. Only future events use the new configuration.

**Does the Event Editor change my Shopify data?** No. Customizations run in Littledata's server-side pipeline after we receive the event. The original Shopify data is never modified, and removing a customization restores the default behavior immediately.

**Do my changes affect other destinations?** No. Every customization belongs to one event on one connection. A mapping change on `purchase` for GA4 has no effect on `purchase` going to Meta or anywhere else.

**Which destinations support the Event Editor?** All destinations Littledata supports. Each connection has its own Events tab.

**Can I customize client-side events?** Client-side events can only be [enabled or disabled](/event-editor/enable-disable-events.md). Editing mappings and trigger conditions is available for server-side events, both standard and custom.

**Can I apply several customizations to one event?** Yes. An event can have trigger conditions, changed mappings, and custom parameters at the same time.

### Sending and trigger conditions

**What's the difference between disabling an event and adding trigger conditions?** Disabling is all or nothing: the event is never sent. [Trigger conditions](/event-editor/trigger-conditions.md) keep the event enabled but only send it when the conditions match. Use disable for "never", conditions for "only when".

**Why did my event stop sending?** Check two things in the event editor: whether the event is disabled, and whether its trigger conditions are stricter than intended. With ALL logic, one wrong condition stops every event from matching.

**Why is my destination receiving two events for one purchase?** A [custom event](/event-editor/custom-events.md) based on `purchase` with no trigger conditions fires alongside the original on every purchase. Add conditions to the custom event so it only fires in the scenario it was made for.

**Do multiple conditions combine with AND or OR?** You choose per event: **ALL of the following are true** (every condition must match) or **ANY of the following are true** (one match is enough).

### Custom events

**Do custom events start with an empty payload?** No. A custom event inherits the complete field mappings of its base event, so it sends a full, valid payload from the moment it's created. You then edit whatever the variation needs.

**Can I base a custom event on another custom event?** No. Custom events can only be based on standard events.

**Can I use the same custom event in several destinations?** A custom event exists only in the connection where you created it. To use it elsewhere, create it in that connection too.

**Does creating a custom event change the original event?** No. The base event keeps working exactly as before.

**If I disable the base event, what happens to custom events based on it?** They're disabled too. Disabling a standard event currently disables every custom event built on it. This is a current limitation.

**Are custom events market-specific when Shopify Markets is enabled?** No. If Shopify Markets is enabled in Littledata, a custom event created in one market is created for every market. To scope one to a single market, add [trigger conditions](/event-editor/trigger-conditions.md) on the market fields (`market_id` or handle, see the [Tracking schema glossary](/event-editor/glossary.md#market)).

### Field mappings

**What is a locked mapping?** A [mapping](/event-editor/field-mappings.md) required by the destination platform. Both the source and the destination are read-only.

**Can I remove a standard mapping?** No. You can change its source, but the destination field stays.

**What happens if a mapped field is missing or the path is wrong?** Littledata skips that mapping for that event. The event still sends. Use the [event preview](/event-editor/event-preview.md) to spot empty values before saving.

**Is there a limit on custom parameters?** Yes, and it varies by destination. The **Add parameter** button disables when you reach it.

**Are mapping changes market-specific when Shopify Markets is enabled?** No. If Shopify Markets is enabled in Littledata, a customization on a standard event applies across all markets.

### Custom Data Sources

**My metafield doesn't appear in the setup dropdown.** Click **Refresh metafields** and give it a few minutes to discover the store's metafields, then check again.

**My metafield doesn't appear in the Event Editor.** Only metafields you've selected and saved in the [Custom data sources setup](/event-editor/custom-data-sources.md) are exposed to the Event Editor. Go back to the source settings and confirm it's added.

**My metafield is mapped but the value is empty on some events.** Metafield availability depends on the event type. Customer metafields are available on order and customer events, product metafields on product and order events, and variant metafields on add to cart and order events.

**Can I pull in cookies or local storage values?** Not yet. Storefront data sources are coming soon; metafields are available today.

### Event preview

**The preview doesn't respect my trigger conditions.** Trigger conditions aren't evaluated in the [preview](/event-editor/event-preview.md). It shows what the payload will look like when the event is sent, not whether a given event would be sent.

**The preview shows an outdated value.** The preview is built from a stored historical event, so very recent changes on your store, like newly added metafield values, may not appear yet.