Change Device language via ADB

Your errors have nothing to do with adb. You just lack understanding of how your local shell processes your command. What you are doing is running these commands locally (on your PC):

adb shell setprop persist.sys.language fr
setprop persist.sys.country CA
stop
sleep 5
start

and the error messages you see are from local shell (i.e. there is no setprop executable on your system and start and stop commands have non-optional parameters.

the correct command would be

adb shell "setprop persist.sys.language fr; setprop persist.sys.country CA; setprop ctl.restart zygote"

or in more recent Android versions:

adb shell "setprop persist.sys.locale fr-CA; setprop ctl.restart zygote"

You can change the locale/language for testing purposes without rooting the device, also on newer (4.2+) devices. You have to create an application that changes the device locale. Or, you can use a helper app, e.g. ADB Change Language.

Next, on 4.2+ devices, you have to use grant the app CHANGE_CONFIGURATION permission via adb, adb shell pm grant <package_name> android.permission.CHANGE_CONFIGURATION.

Finally, you can use adb commands (launch activity) to switch locale.

There is few solutions.It works for me.

1.

adb shell am start -a android.settings.LOCALE_SETTINGS (You could see the language menu, then choose language by appium)

2.

download adbchangelanguage on google store

adb shell pm grant net.sanapeli.adbchangelanguage android.permission.CHANGE_CONFIGURATION

adb shell am start -n net.sanapeli.adbchangelanguage/.AdbChangeLanguage -e language zh -e country TW

https://gist.github.com/douglasselph/b9998e69998759c6cceec1df1aa96ac5

3.

using appium then set desired capabilities (language and locale) http://appium.io/docs/en/writing-running-appium/caps/

This is all over the place, to put it simply

setprop will only work on an AVD or a rooted physical device

The alternative is to use the settings in the Launcher.

Rooted device or AVD this works:

<android-sdk path>/platform-tools/adb shell
root@generic:/ # getprop persist.sys.language
getprop persist.sys.language
en
root@generic:/ # setprop persist.sys.language fr
setprop persist.sys.language fr
root@generic:/ # setprop persist.sys.country CA
setprop persist.sys.country CA
root@generic:/ # stop
stop
root@generic:/ # start
start
root@generic:/ # sleep 5
sleep 5
root@generic:/ # getprop |grep lang
getprop |grep lang
[persist.sys.language]: [fr]
root@generic:/ # getprop |grep country
getprop |grep country
[persist.sys.country]: [CA]
root@generic:/ #

Run through the following steps:

• Create emulator with google APIs Intel x86

• Root the emulator, by running the command:

  adb root
  

• Run the following shell command through adb:

  adb -e shell "su root; setprop persist.sys.locale pt-PT; stop; sleep 2; start” 
  

  then, exit the shell which restarts the emulator.

• Locales we need for screenshots:

  de_DE
  en_EN
  fr_FR
  ko_KO
  pt_PT
  es_ES
  ja_JA