scrcpy/FAQ.md

Frequently Asked Questions

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Here are the common reported problems and their status.

adb issues

scrcpy execute adb commands to initialize the connection with the device. If adb fails, then scrcpy will not work.

In that case, it will print this error:

ERROR: "adb get-serialno" returned with value 1

This is typically not a bug in scrcpy, but a problem in your environment.

To find out the cause, execute:

adb devices

adb not found

You need adb accessible from your PATH.

On Windows, the current directory is in your PATH, and adb.exe is included in the release, so it should work out-of-the-box.

Device unauthorized

error: device unauthorized.
This adb server's $ADB_VENDOR_KEYS is not set
Try 'adb kill-server' if that seems wrong.
Otherwise check for a confirmation dialog on your device.

When connecting, a popup should open on the device. You must authorize USB debugging.

If it does not open, check stackoverflow.

Device not detected

error: no devices/emulators found

Check that you correctly enabled adb debugging.

If your device is not detected, you may need some drivers (on Windows). There is a separate USB driver for Google devices.

Several devices connected

If several devices are connected, you will encounter this error:

error: more than one device/emulator

the identifier of the device you want to mirror must be provided:

scrcpy -s 01234567890abcdef

Note that if your device is connected over TCP/IP, you might get this message:

adb: error: more than one device/emulator
ERROR: "adb reverse" returned with value 1
WARN: 'adb reverse' failed, fallback to 'adb forward'

This is expected (due to a bug on old Android versions, see #5), but in that case, scrcpy fallbacks to a different method, which should work.

Conflicts between adb versions

adb server version (41) doesn't match this client (39); killing...

This error occurs when you use several adb versions simultaneously. You must find the program using a different adb version, and use the same adb version everywhere.

You could overwrite the adb binary in the other program, or ask scrcpy to use a specific adb binary, by setting the ADB environment variable:

set ADB=/path/to/your/adb
scrcpy

Device disconnected

If scrcpy stops itself with the warning "Device disconnected", then the adb connection has been closed.

Try with another USB cable or plug it into another USB port. See #281 and #283.

Control issues

Mouse and keyboard do not work

On some devices, you may need to enable an option to allow simulating input. In developer options, enable:

USB debugging (Security settings)
Allow granting permissions and simulating input via USB debugging

Special characters do not work

The default text injection method is limited to ASCII characters. A trick allows to also inject some accented characters, but that's all. See #37.

Since scrcpy v1.20 on Linux, it is possible to simulate a physical keyboard (HID).

Client issues

The quality is low

If the definition of your client window is smaller than that of your device screen, then you might get poor quality, especially visible on text (see #40).

This problem should be fixed in scrcpy v1.22: update to the latest version.

On older versions, you must configure the scaling behavior:

scrcpy.exe > Properties > Compatibility > Change high DPI settings > Override high DPI scaling behavior > Scaling performed by: Application.

Also, to improve downscaling quality, trilinear filtering is enabled automatically if the renderer is OpenGL and if it supports mipmapping.

On Windows, you might want to force OpenGL to enable mipmapping:

scrcpy --render-driver=opengl

Issue with Wayland

By default, SDL uses x11 on Linux. The video driver can be changed via the SDL_VIDEODRIVER environment variable:

export SDL_VIDEODRIVER=wayland
scrcpy

On some distributions (at least Fedora), the package libdecor must be installed manually.

See issues #2554 and #2559.

KWin compositor crashes

On Plasma Desktop, compositor is disabled while scrcpy is running.

As a workaround, disable "Block compositing".

Crashes

Exception

There may be many reasons. One common cause is that the hardware encoder of your device is not able to encode at the given definition:

ERROR: Exception on thread Thread[main,5,main]
android.media.MediaCodec$CodecException: Error 0xfffffc0e
...
Exit due to uncaughtException in main thread:
ERROR: Could not open video stream
INFO: Initial texture: 1080x2336

or

ERROR: Exception on thread Thread[main,5,main]
java.lang.IllegalStateException
        at android.media.MediaCodec.native_dequeueOutputBuffer(Native Method)

Just try with a lower definition:

scrcpy -m 1920
scrcpy -m 1024
scrcpy -m 800

Since scrcpy v1.22, scrcpy automatically tries again with a lower definition before failing. This behavior can be disabled with --no-downsize-on-error.

You could also try another encoder.

If you encounter this exception on Android 12, then just upgrade to scrcpy >= 1.18 (see #2129):

> ERROR: Exception on thread Thread[main,5,main]
java.lang.AssertionError: java.lang.reflect.InvocationTargetException
    at com.genymobile.scrcpy.wrappers.SurfaceControl.setDisplaySurface(SurfaceControl.java:75)
    ...
Caused by: java.lang.reflect.InvocationTargetException
    at java.lang.reflect.Method.invoke(Native Method)
    at com.genymobile.scrcpy.wrappers.SurfaceControl.setDisplaySurface(SurfaceControl.java:73)
    ... 7 more
Caused by: java.lang.IllegalArgumentException: displayToken must not be null
    at android.view.SurfaceControl$Transaction.setDisplaySurface(SurfaceControl.java:3067)
    at android.view.SurfaceControl.setDisplaySurface(SurfaceControl.java:2147)
    ... 9 more

Command line on Windows

Since v1.22, a "shortcut" has been added to directly open a terminal in the scrcpy directory. Double-click on open_a_terminal_here.bat, then type your command. For example:

scrcpy --record file.mkv

You could also open a terminal and go to the scrcpy folder manually:

1. Press Windows+r, this opens a dialog box.

2. Type cmd and press Enter, this opens a terminal.

3. Go to your scrcpy directory, by typing (adapt the path):

   cd C:\Users\user\Downloads\scrcpy-win64-xxx
   

   and press Enter

4. Type your command. For example:

   scrcpy --record file.mkv
   

If you plan to always use the same arguments, create a file myscrcpy.bat (enable show file extensions to avoid confusion) in the scrcpy directory, containing your command. For example:

scrcpy --prefer-text --turn-screen-off --stay-awake

Then just double-click on that file.

You could also edit (a copy of) scrcpy-console.bat or scrcpy-noconsole.vbs to add some arguments.

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