Sonos Ace firmware updates run through the Sonos app, and the 2024 redesign of that app made a straightforward process unexpectedly unreliable. A stuck update usually means a permission is missing, the battery dipped too low, or a background process froze inside the app. Running through these checks in order saves the most time, most of them take under a minute.
Check the Sonos App Permissions First
Open your phone's main Settings app, scroll to the app list, and tap Sonos. Tap Permissions and make sure Location and Nearby Devices (Android) or Bluetooth (iOS) are set to Allow. Without these, the app cannot talk to the Ace to push the firmware file. This is the single most common reason updates fail on the current Sonos app version, and it is an easy miss during initial setup.
Clear the App Cache, Not Your Data
The Sonos app caches firmware files locally. If the first download dropped out partway through, the cache holds a broken copy and every retry tries to reuse that same bad file. On Android, go to Settings > Apps > Sonos > Storage > Clear cache. On iOS, offloading the app and reinstalling it does the same thing without wiping your login.
Do not tap Clear Data or Delete App unless the cache clear alone fails. Those steps log you out and erase your saved speaker configurations. After clearing the cache, reopen the Sonos app and try the update again.
Plug the Headphones Into Power
The Sonos Ace needs at least 30% charge to accept a firmware update. Plug the USB-C cable into the left earcup and a 5W (or higher) power adapter. Leave it plugged in for at least 15 minutes before starting the process.
If you plan to use the wired USB-C audio mode later, do not plug the cable into a computer or phone for audio during the update. The update requires the standard USB-C charging handshake, not audio passthrough. Keep it on a dedicated charger until the firmware finishes.
Reset the Sonos Ace the Official Way
If the update keeps hanging at the exact same spot, the headphones are likely in a half-updated state. The official reset method is unique: hold the Power/Bluetooth button down, then plug the USB-C cable into a charger while still holding the button. Keep holding it until the LED on the earcup flashes.
This is the full factory reset, and it clears whatever partial state is blocking the firmware from applying. After the reset, re-pair the Ace in the Sonos app as if they were brand new. The app will offer the firmware update again, and a clean post-reset update almost always goes through.
Keep Your Phone Close During the Update
Firmware updates over Bluetooth do not like distance or interference. The Sonos app sends the firmware file to the headphones over Bluetooth, and if the phone goes to sleep, switches to a cellular tower, or you walk more than 15 feet away, the transfer aborts silently. Place the phone next to the Ace on a table, disable the screen timeout for a few minutes, and let the progress bar run without touching either device.
Update the Sonos App Itself
Sometimes the failure is entirely on the app side, not the headphones. The 2024 Sonos app redesign has shipped several rapid bug fixes. Open the App Store or Google Play Store, search for Sonos, and tap Update if you see one available. Running a version from three months ago may have a known bug that prevents pulling newer Ace firmware.
After updating the app, try the firmware update immediately. Newer app versions sometimes expect the latest firmware to function correctly with the Ace.
Don't Confuse a TV Audio Swap Issue With a Firmware Issue
If you are updating the Ace specifically to use TV Audio Swap, double-check your soundbar. TV Audio Swap only works with Sonos Arc, Beam Gen 2, or Ray. If the firmware update goes through but Swap still does not work, the soundbar itself likely needs a firmware update too. Open the Sonos app, tap the soundbar, and check for pending updates on that device.
Reinstall the Sonos App if Nothing Else Clicked
The redesigned Sonos app has persistent bugs that survive cache clears. Deleting the app entirely, rebooting your phone, and installing a fresh copy from the App Store or Google Play Store resolves update loops that look like a headphone hardware problem but are actually a corruption in the app's local database.
After the fresh install, log back into your Sonos account and tap the Ace in the device list. The app should pick up the pending update within a minute and prompt you to resume.
Wait Out a Bad Firmware Pull
Sonos occasionally releases a firmware update, discovers a regression, and pulls it from distribution without an announcement. If the update fails for you at every step and online forums show similar complaints from other Ace owners dated within the same 48-hour window, the version may have been withdrawn. Give it 24 to 48 hours, then retry. The app will automatically fetch the newest published version when it becomes available.
