Update Samsung Galaxy S3 i9300 to Marshmallow using CM13 Custom ROM


Samsung Galaxy S3 is still a popular smartphone by Samsung but S3 won’t get official Marshmallow Update. But don’t worry you can still have Marshmallow on your Galaxy S3 by flashing CM13 custom ROM on it. In 2012 Samsung Galaxy S3 was the hottest android smartphone and Samsung sold about 50 million sets during the year of its launch and now this amazing smartphone has forgotten but not by third parties developers like CM. So CM13 ROM will give you whatever you need as it is based on the latest Android version marshmallow.
S3 came running Android 4.0 Ice cream sandwich and got several jellybean updates but after that no new updates for this awesome smartphone has been released but now you can upgrade it to Android 6.0.1 via CM13. CM12 for some S3 variants is also in market based on lollipop but Marshmallow is the latest one why go for the old one. Follow our simple step by step guide to flash CM13 on your Samsung S3 i9300.

CM13 Marshmallow features

 Android 6.0.1 based CM13 custom ROM has many cool features like Doze mode (battery saver), multi window support, new system UI and many other customizations along with fast performance. There are no known bugs in this ROM, all issues are being fixed and everything works fine.
 Note: Flashing custom ROM needs a rooted device along with custom recoveries like Clockwork mod or TWRP. So before flashing make sure you have a rooted device with recovery installed.


* Create a complete backup of all your important data, apps, texts, contacts, call logs and other multimedia files.
* Charge your phone battery at least 70% to avoid power related issues.
* Enable USB debugging mode in settings menu.


This guide is only for Samsung Galaxy S3 (i9300), Do Not try this on any other device or you may end up bricking your device. Flashing custom ROM voids device warranty so do it on your own risk.

download links

 Cm13 file

Gapps file

Flashing CM13 ROM on S3 (i9300)

1. After downloading connect your S3 with PC using USB cable and copy the CM13 and Gapps zip files to your device SD card.

2. Unplug your S3 and turn it off and boot it into recovery mode by pressing and holding volume up + Home and power buttons simultaneously.

3. Now you’re in recovery menu here first of all create a Nandroid Backup in Backup option.

4. After that perform a factory reset ( wipe data / factory reset) and also clear the Cache ( wipe cache ) along with Dalvik Cache in Advanced options.

5. After wiping all data go back to the main recovery menu and tap Install zip option.

6. Now navigate for CM13 zip file and select it for installation. In TWRP recovery swipe to install.

7. After CM13 again install zip but this time Gapps.zip file and flash it.
Once done, go back to the main menu and Reboot your device. Congrats! You’ve successfully flashed CM13 Marshmallow based custom ROM on your Galaxy S3 (i9300). Drop a comment if you’ve any queries.