[G3 Q&A, Help & Troubleshooting] booboss:
Hello everyone,

I've upgraded stock Lolipop to stock Marshmallow and rooted. Now I can't get RW access to SD card. There are several apps in Google Play to gain RW access and they worked on Lolipop. Now on M none of them works. I've also tried "manual" method described here but the problem is that my file doesn't contain lines which should be changed in this tutorial. According to tutorial there should be a section with WRITE_EXTERNAL_STORAGE but the only simmilar I've found is WRITE_MEDIA_STORAGE wchich probably reffers to something else.

Here's my file (/system/etc/permissions/platform.xml):

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright (C) 2008 The Android Open Source Project

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
-->

<!-- This file is used to define the mappings between lower-level system
user and group IDs and the higher-level permission names managed
by the platform.

Be VERY careful when editing this file! Mistakes made here can open
big security holes.
-->
<permissions>

<!-- ================================================================== -->
<!-- ================================================================== -->
<!-- ================================================================== -->

<!-- The following tags are associating low-level group IDs with
permission names. By specifying such a mapping, you are saying
that any application process granted the given permission will
also be running with the given group ID attached to its process,
so it can perform any filesystem (read, write, execute) operations
allowed for that group. -->

<permission name="android.permission.BLUETOOTH_ADMIN" >
<group gid="net_bt_admin" />
</permission>

<permission name="android.permission.BLUETOOTH" >
<group gid="net_bt" />
</permission>

<permission name="android.permission.BLUETOOTH_STACK" >
<group gid="net_bt_stack" />
</permission>

<permission name="android.permission.NET_TUNNELING" >
<group gid="vpn" />
</permission>

<permission name="android.permission.INTERNET" >
<group gid="inet" />
</permission>

<permission name="android.permission.READ_LOGS" >
<group gid="log" />
</permission>

<permission name="android.permission.WRITE_MEDIA_STORAGE" >
<group gid="media_rw" />
<group gid="sdcard_rw" />
</permission>

<permission name="android.permission.ACCESS_MTP" >
<group gid="mtp" />
</permission>

<permission name="android.permission.NET_ADMIN" >
<group gid="net_admin" />
</permission>

<!-- The group that /cache belongs to, linked to the permission
set on the applications that can access /cache -->
<permission name="android.permission.ACCESS_CACHE_FILESYSTEM" >
<group gid="cache" />
</permission>

<!-- RW permissions to any system resources owned by group 'diag'.
This is for carrier and manufacture diagnostics tools that must be
installable from the framework. Be careful. -->
<permission name="android.permission.DIAGNOSTIC" >
<group gid="input" />
<group gid="diag" />
</permission>

<!-- Group that can read detailed network usage statistics -->
<permission name="android.permission.READ_NETWORK_USAGE_HISTORY">
<group gid="net_bw_stats" />
</permission>

<!-- Group that can modify how network statistics are accounted -->
<permission name="android.permission.MODIFY_NETWORK_ACCOUNTING">
<group gid="net_bw_acct" />
</permission>

<permission name="android.permission.LOOP_RADIO" >
<group gid="loop_radio" />
</permission>

<!-- Hotword training apps sometimes need a GID to talk with low-level
hardware; give them audio for now until full HAL support is added. -->
<permission name="android.permission.MANAGE_VOICE_KEYPHRASES">
<group gid="audio" />
</permission>

<permission name="android.permission.ACCESS_FM_RADIO" >
<group gid="media" />
</permission>

<!-- ================================================================== -->
<!-- ================================================================== -->
<!-- ================================================================== -->

<!-- The following tags are assigning high-level permissions to specific
user IDs. These are used to allow specific core system users to
perform the given operations with the higher-level framework. For
example, we give a wide variety of permissions to the shell user
since that is the user the adb shell runs under and developers and
others should have a fairly open environment in which to
interact with the system. -->

<assign-permission name="android.permission.MODIFY_AUDIO_SETTINGS" uid="media" />
<assign-permission name="android.permission.ACCESS_SURFACE_FLINGER" uid="media" />
<assign-permission name="android.permission.WAKE_LOCK" uid="media" />
<assign-permission name="android.permission.UPDATE_DEVICE_STATS" uid="media" />
<assign-permission name="android.permission.UPDATE_APP_OPS_STATS" uid="media" />

<assign-permission name="android.permission.ACCESS_SURFACE_FLINGER" uid="graphics" />

<!-- This is a list of all the libraries available for application
code to link against. -->

<library name="android.test.runner"
file="/system/framework/android.test.runner.jar" />
<library name="javax.obex"
file="/system/framework/javax.obex.jar" />
<library name="org.apache.http.legacy"
file="/system/framework/org.apache.http.legacy.jar" />

<!-- These are the standard packages that are white-listed to always have internet
access while in power save mode, even if they aren't in the foreground. -->
<allow-in-power-save-except-idle package="com.android.providers.downloads" />

</permissions>

I've also tried to add the whole section mentioned in tutorial manualy but that didn't work either.

Does anybody have any idea or at least can post his own file from Android M on LG G3?