The map is blank or grey

A respondent reports a grey rectangle, a map with markers but no streets or imagery behind them, or an empty space where the survey should be when it is embedded in another site.

Why it happens

The map is drawn in the respondent’s browser from several sources, and any of them can be blocked on their side.

• Background tiles are blocked. Streets and Topo basemaps come from Mapbox, Satellite from Esri. A corporate network, a strict ad blocker or a privacy extension leaves the markers over a grey background.
• The map library is blocked. The map code loads from unpkg.com and cdnjs.cloudflare.com; if those are blocked the map area stays empty.
• The survey is embedded on a site that is not allowed to frame it. When Sites allowed to embed on the share page lists specific sites, a page on any other host gets an empty frame. A host page served over plain http:// cannot frame the survey either.
• Third-party cookies are blocked in the embed. The survey shows, but answers do not persist from page to page.
• The browser is out of date. Browsers several years old do not run the map code.
• Self-hosted installation without a map token. Streets and Topo need a Mapbox access token in the configuration.

What to do

1. Ask the respondent to open the survey link directly, outside any embed, in a current browser. If the map appears there, the embed or their extensions are the cause.
2. Ask them to disable ad-blocking and privacy extensions for the survey page, or to try another network.
3. If the survey is embedded, open the share page and check Sites allowed to embed. Add the host of the embedding page and click Save allowed sites, or leave the list empty to let any site embed. The host page must use https://. See Embed a survey.
4. If answers are lost between pages inside an embed, ask the respondent to open the link directly.
5. On a self-hosted instance, set the Mapbox token described in the project README and restart.

If it keeps happening

Contact support with the survey link, the respondent’s browser and device, whether the survey was opened directly or embedded (and where), and a screenshot. The first red line in the browser’s developer console tells us which request was blocked.