Firefox uses its own extension identity and native-host registration, even though downloads arrive in the same Flux desktop queue. Use the Firefox package rather than loading the Chromium ZIP. The release provides separate compatibility packages for Firefox 140+ and Firefox 120–139; choose the one matching your browser.
The application-to-browser connection
Flux’s desktop startup can register or repair the Firefox native messaging host. The extension must still be installed, enabled and granted the requested consent and site permissions. Refresh already-open pages after installation. A visible media button alone does not prove that the desktop bridge is connected.
Installation and signing are separate
The published GitHub ZIPs are unsigned. Permanent Firefox installation requires Mozilla signing, so follow the current release’s documented loading route rather than expecting a ZIP to behave like an approved AMO listing. The application can repair its local host registration, but it cannot grant Mozilla’s signature or replace browser approval.
A focused troubleshooting sequence
- Confirm the Firefox compatibility package and desktop release.
- Enable the extension and check consent and site access.
- Launch Flux once, then reload the page.
- If connection fails, repair the browser bridge in Settings.
- Test an ordinary attachment before investigating a particular video provider.
Media source availability still matters
After a successful handoff, review resolution, output and destination in the desktop approval window. Firefox support does not remove provider restrictions: DRM, CAPTCHA, unavailable streams and session challenges can still prevent a transfer. Keep the error message and source context when reporting a problem, but do not publish cookies or authorization headers in a public issue.
Sources and release context
This guide describes the Flux 2.6.6 documentation. Check the current release record for package conditions.
