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Samsung DeX on a Mac not working? 10 fixes

Most problems come down to four things. USB debugging isn't authorized, the cable only charges, the phone is older than One UI 8, or the phone has gone to sleep or locked. Find your symptom below. Each fix works whether you run DeX with scrcpy or with Deskbridge.

Updated October 24, 2026 · Tested on a Galaxy Z Fold 7 (One UI 9) with scrcpy 5.0.1 on macOS

1. The Mac doesn't see the phone at all

Run adb devices in Terminal (Deskbridge users: the menu says "Waiting for your phone"). An empty list means no data connection.

• Try another cable. This is the most common cause by far. Many USB-C cables, especially ones that came with chargers or power banks, are charge-only. Use the cable that came with the phone, or any cable sold for data or video.
• Skip the hub. Plug straight into the Mac. Some hubs and monitor docks pass power but not a reliable data link.
• USB debugging must be on: Settings › About phone › Software information, tap Build number seven times, then Settings › Developer options › USB debugging.
• Check the USB mode. If the phone shows a "USB for" notification, pick Transferring files / Android Auto rather than charging only.

2. adb says "unauthorized"

The phone sees the Mac but hasn't trusted it yet. Unlock the phone and look for Allow USB debugging?. Tick Always allow from this computer and tap Allow. No prompt? Unplug, plug back in with the phone unlocked. Still nothing? Developer options › Revoke USB debugging authorizations, then reconnect and accept the new prompt.

3. I see my phone's screen, not DeX

You're mirroring the phone rather than giving it a second display. Two causes:

• The phone is older than One UI 8. DeX only starts on a virtual display from One UI 8 onward. Check Settings › About phone › Software information › One UI version. See which phones support DeX on a Mac.
• scrcpy without --new-display. Plain scrcpy mirrors. You need scrcpy --new-display=1920x1080/160, and scrcpy 3.0 or later (scrcpy --version).

4. The window opens and closes straight away

With scrcpy, read the last lines it prints. The usual culprits are an old scrcpy (update with brew upgrade scrcpy), an H.265 encoder the phone won't start (switch to --video-codec=h264), or an odd resolution (keep width and height multiples of 8). Another app holding adb, such as Android Studio or a second scrcpy, can also get in the way, so quit it and retry.

5. DeX froze or the window went black

The phone went to sleep. A sleeping Galaxy pauses its DeX display, and that happens if you press the power button or let the screen time out. It also happens with scrcpy's --turn-screen-off, which puts Samsung phones into doze. Wake the phone's own display:

adb shell input -d 0 keyevent KEYCODE_WAKEUP

To stop it happening, keep the phone awake (--stay-awake while plugged in) and never use --turn-screen-off for DeX. Deskbridge notices a sleeping phone within a couple of seconds and wakes it. Its Secure Blackout keeps the phone screen dark without letting it sleep.

6. The dock has no apps, no clock, and I can't type

Your phone is locked. While the lock screen is up, Samsung shrinks the DeX dock to bare navigation buttons and blocks typing. That's a security rule, not a fault. Unlock the phone (the fingerprint sensor works without opening a foldable) and the full dock comes back. In Deskbridge, Unlock Phone… (⌥⌘U) lets you type the PIN on your Mac.

7. Everything is blurry, tiny or huge

The display's DPI doesn't match its size. Keep a "1080p-sized" layout with DPI = 160 × width ÷ 1920: 1920x1080/160, 2560x1440/213 or 3840x2160/320 for a Retina-sharp window. For a portrait window that acts like a big phone rather than a tablet, use 160 × short edge ÷ 480, so 1080x1920/360. In Deskbridge, use Display Size and Text Size in the menu.

8. No sound on the Mac

Audio forwarding needs Android 11 or later. Check the Mac's output device and volume. In Deskbridge, make sure Play Phone Audio on Mac is ticked. With scrcpy, audio is on by default, so look for an audio error in its output, and don't pass --no-audio.

9. Keyboard shortcuts do the wrong thing

macOS grabs some ⌘ shortcuts before the phone sees them. With scrcpy, --shortcut-mod=lsuper,rsuper makes ⌘ scrcpy's shortcut key (lcmd isn't a valid name). Then ⌘H goes home, ⌘B back and ⌘S to recent apps. Right-click also means Back. If a shortcut opens a Mac app instead, it's probably a system shortcut. Change it in System Settings › Keyboard › Keyboard Shortcuts.

10. Wireless worked yesterday, not today

Wireless debugging connections end when the phone restarts or changes network, and the port changes each time. Re-pair from Developer options › Wireless debugging › Pair device with pairing code, or plug in once. The phone and Mac must be on the same Wi-Fi network, and some guest or office networks block devices from seeing each other. Over Wi-Fi the phone isn't charging, so --stay-awake does nothing. Keep an eye on sleep.