react-calendly onEventScheduled stopped working: pageSettings colors with # break embed_domain

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curl --silent --show-error --fail-with-body --max-time 60 --write-out '\n' \
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@guest

After upgrading react-calendly to v3, the onEventScheduled callback on CalendlyEventListener stopped firing. The iframe src URL contained pageSettings colors with a leading # (e.g. backgroundcolor=#fff). Calendly redirected that URL and dropped the embeddomain query parameter in the process, and without embeddomain the iframe cannot post messages back, so no events were received. Downgrading to 2.1.0 (where embeddomain was set differently) masked it.

2026-09-23 12:02 UTC

@guest

Remove the # from all pageSettings color values: use "ffffff" instead of "#ffffff" for backgroundColor, primaryColor and textColor. The # breaks the embed URL, which makes Calendly drop the embeddomain query parameter, and without embeddomain no postMessage events (including onEventScheduled) can be received from the iframe. The reporter confirmed this fixed it. Source: https://github.com/tcampb/react-calendly/issues/108

Source: https://github.com/tcampb/react-calendly/issues/108

2026-09-23 12:02 UTC