Style not found error when displaying date-valued features in local time zone in Mapbox GL JS

Answer the exact question first

Where to convert timestamps? Convert them in the data‑preparation phase, i.e. before you call map.addSource or source.setData. The style URL is independent of the source data, so changing the source cannot invalidate the style.

How to confirm the style URL stays valid? Verify the style request in the Network tab (HTTP 200). The style URL must be a valid mapbox://styles/… identifier and your access token must have the styles:read scope. Updating the source never triggers a style fetch, so no new error will appear unless the style URL itself is wrong.

Patterns that guarantee correct local‑time rendering without style errors:

• Store timestamps as UTC ISO‑8601 strings (e.g., 2026-10-14T12:00:00Z).
• During data‑prep, convert each timestamp to the target time zone using a reliable library (e.g., luxon or Date.prototype.toLocaleString with timeZone).
• Replace the original property (or add a new one) with the converted string or epoch value.
• Pass the fully‑converted GeoJSON to map.addSource or source.setData.
• In the style, reference the converted property with get and format it with to-string or string concatenation. No time‑zone logic is needed in the expression.

Minimal reproducible example

const sourceData = {
  type: 'FeatureCollection',
  features: originalFeatures.map(f => ({
    ...f,
    properties: {
      ...f.properties,
      localTime: luxon.DateTime.fromISO(f.properties.utcTime, {zone: 'America/New_York'}).toLocaleString(luxon.DateTime.DATETIME_SHORT)
    }
  }))
};

map.addSource('events', {type: 'geojson', data: sourceData});

map.addLayer({
  id: 'event-label',
  type: 'symbol',
  source: 'events',
  layout: {
    'text-field': ['get', 'localTime'],
    'text-size': 12
  }
});

Verification checklist

1. Open the browser console and check that the style request returns 200.
2. Log the localTime property of a few features before setData to ensure it is already in the desired format.
3. Refresh the map and confirm labels display the expected local time.
4. If a style error appears, isolate it by loading a known good style URL (e.g., mapbox://styles/mapbox/streets-v12) and see if the error persists.

Need more details?

Does your style URL contain a custom style ID that might have been deleted or renamed? If the style error persists after confirming the URL, please share the exact style ID and the token’s scopes. That information will help pinpoint whether the issue is with the style itself or with the data pipeline.