# Frequently Asked Questions [Read in another language](#translations) Here are the common reported problems and their status. If you encounter any error, the first step is to upgrade to the latest version. ## `adb` issues `scrcpy` execute `adb` commands to initialize the connection with the device. If `adb` fails, then scrcpy will not work. This is typically not a bug in _scrcpy_, but a problem in your environment. ### `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 not detected > ERROR: Could not find any ADB device Check that you correctly enabled [adb debugging][enable-adb]. Your device must be detected by `adb`: ``` adb devices ``` If your device is not detected, you may need some [drivers] (on Windows). There is a separate [USB driver for Google devices][google-usb-driver]. [enable-adb]: https://developer.android.com/studio/command-line/adb.html#Enabling [drivers]: https://developer.android.com/studio/run/oem-usb.html [google-usb-driver]: https://developer.android.com/studio/run/win-usb ### Device unauthorized > ERROR: Device is unauthorized: > ERROR: --> (usb) 0123456789abcdef unauthorized > ERROR: A popup should open on the device to request authorization. When connecting, a popup should open on the device. You must authorize USB debugging. If it does not open, check [stackoverflow][device-unauthorized]. [device-unauthorized]: https://stackoverflow.com/questions/23081263/adb-android-device-unauthorized ### Several devices connected If several devices are connected, you will encounter this error: > ERROR: Multiple (2) ADB devices: > ERROR: --> (usb) 0123456789abcdef device Nexus_5 > ERROR: --> (tcpip) 192.168.1.5:5555 device GM1913 > ERROR: Select a device via -s (--serial), -d (--select-usb) or -e (--select-tcpip) In that case, you can either provide the identifier of the device you want to mirror: ```bash scrcpy -s 0123456789abcdef ``` Or request the single USB (or TCP/IP) device: ```bash scrcpy -d # USB device scrcpy -e # TCP/IP device ``` 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. [#5]: https://github.com/Genymobile/scrcpy/issues/5 ### 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: ```bash # in bash export ADB=/path/to/your/adb scrcpy ``` ```cmd :: in cmd set ADB=C:\path\to\your\adb.exe scrcpy ``` ```powershell # in PowerShell $env:ADB = 'C:\path\to\your\adb.exe' 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]. [#281]: https://github.com/Genymobile/scrcpy/issues/281 [#283]: https://github.com/Genymobile/scrcpy/issues/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_ [simulating input]: https://github.com/Genymobile/scrcpy/issues/70#issuecomment-373286323 ### Special characters do not work The default text injection method is [limited to ASCII characters][text-input]. A trick allows to also inject some [accented characters][accented-characters], but that's all. See [#37]. Since scrcpy v1.20 on Linux, it is possible to simulate a [physical keyboard][hid] (HID). [text-input]: https://github.com/Genymobile/scrcpy/issues?q=is%3Aopen+is%3Aissue+label%3Aunicode [accented-characters]: https://blog.rom1v.com/2018/03/introducing-scrcpy/#handle-accented-characters [#37]: https://github.com/Genymobile/scrcpy/issues/37 [hid]: README.md#physical-keyboard-simulation-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]). [#40]: https://github.com/Genymobile/scrcpy/issues/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_. [scaling behavior]: https://github.com/Genymobile/scrcpy/issues/40#issuecomment-424466723 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: [video driver]: https://wiki.libsdl.org/FAQUsingSDL#how_do_i_choose_a_specific_video_driver ```bash export SDL_VIDEODRIVER=wayland scrcpy ``` On some distributions (at least Fedora), the package `libdecor` must be installed manually. See issues [#2554] and [#2559]. [#2554]: https://github.com/Genymobile/scrcpy/issues/2554 [#2559]: https://github.com/Genymobile/scrcpy/issues/2559 ### KWin compositor crashes On Plasma Desktop, compositor is disabled while _scrcpy_ is running. As a workaround, [disable "Block compositing"][kwin]. [kwin]: https://github.com/Genymobile/scrcpy/issues/114#issuecomment-378778613 ## 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](README.md#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 ``` [#2129]: https://github.com/Genymobile/scrcpy/issues/2129 ## 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): ```bat cd C:\Users\user\Downloads\scrcpy-win64-xxx ``` and press Enter 4. Type your command. For example: ```bat 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: ```bat 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. [show file extensions]: https://www.howtogeek.com/205086/beginner-how-to-make-windows-show-file-extensions/ ## Translations This FAQ is available in other languages: - [Italiano (Italiano, `it`) - v1.19](FAQ.it.md) - [한국어 (Korean, `ko`) - v1.11](FAQ.ko.md) - [简体中文 (Simplified Chinese, `zh-Hans`) - v1.22](FAQ.zh-Hans.md)