The error 

[ ] An unknown server-side error occurred while processing the command. Original error: Error executing adbExec. Original error: 'Command 'C:\\Users\\harc\\AppData\\Local\\Android\\Sdk\\platform-tools\\adb.exe -P 5037 -s 46720e63 shell 'settings delete global hidden_api_policy_pre_p_apps;settings delete global hidden_api_policy_p_apps;settings delete global hidden_api_policy'' exited with code 255'; Stderr: 'Security exception: Permission denial: writing to settings requires:android.permission.WRITE_SECURE_SETTINGS
java.lang.SecurityException: Permission denial: writing to settings requires:android.permission.WRITE_SECURE_SETTINGS
at com.android.providers.settings.SettingsProvider.enforceWritePermission(SettingsProvider.java:1815)
at com.android.providers.settings.SettingsProvider.mutateGlobalSetting(SettingsProvider.java:1023)
at com.android.providers.settings.SettingsProvider.deleteGlobalSetting(SettingsProvider.java:1006)
at com.android.providers.settings.SettingsProvider

is encountered when Silk Test tries to identify and invoke a mobile browser/app on an Android device.

Full article: https://portal.microfocus.com/s/article/KM000015102