Firefox 57 Quantum and Nightly have an audio playback issue in Windows 10 insider build 17063, which has been fixed by Mozilla with help from Microsoft.

Microsoft has recently released Windows 10 build 17063 to insiders in the fast ring with Timeline and Sets features. The build has broke audio in Firefox browser, which was confirmed by Microsoft and acknowledged this was due to the change they made to the Audio Volume APIs.

Windows has several audio volume APIs – IAudioEndpointVolume, IChannelAudioVolume, ISimpleAudioVolume, and IAudioEndpointVolume. These APIs can be used to change the volume and/or mute state of the stream, app, or audio device.

In build 17063 a change was made to these APIs to have them return S_FALSE (1) if the requested change was a no-op.

This broke apps (like Firefox) which request changes (that may be no-ops) and then explicitly check the return value against S_OK (0).

Audio/Sound not playing in Firefox in Windows 10

In this Windows 10 build, when users found audio/sound not working in Firefox, they’ve reported the issue on Feedback Hub.

Microsoft Windows audio and Quality employee informed about the change in latest insider build to reported user on Reddit and provided a workaround, which Mozilla has turned into a patch to fix the issue.

As for now, the issue seems to have been fixed in the Nightly, Firefox 57, Firefox 58 beta and Firefox 52 ESR versions.

The ‘bug 1426719– Latest insider build of Windows 10 (17063) breaks sound playback completely’ has the complete information available.

Are you using latest Windows 10 insider build? Do you’ve any issues with sound in Firefox? Let us know in the comments.