The Samsung Galaxy S2 (GT-I9100) never received an official Android 5.1.1 (Lollipop) update from Samsung; its official support ended with Android 4.1.2 Jelly Bean. To run Android 5.1.1 on this device, you must use custom ROMs developed by the Android community. Firmware Overview Official Version: Android 4.1.2 (Jelly Bean).
Custom Version: Android 5.1.1 (Lollipop) via ROMs like CyanogenMod 12.1 or Resurrection Remix.
Prerequisites: You must have a custom recovery (like TWRP) and a repartitioned internal storage (using a PIT file), as the original system partition is too small for Lollipop. Popular Custom ROMs for Android 5.1.1
CyanogenMod 12.1 (CM12.1): This is the most common base for Lollipop on the GT-I9100. It offers a near-stock Android experience with added customization.
Resurrection Remix: Known for being feature-rich, this ROM combines code from CyanogenMod, Omni, and SlimROMs. gti9100 firmware 511 download upd
LineageOS: While LineageOS usually starts at version 13 (Android 6.0), some unofficial builds of its predecessor (CM) are the primary way to get 5.1.1. Installation Process (High-Level)
Backup Data: Use titanium backup or similar tools, as this will wipe the phone.
Install Custom Recovery: Flash TWRP (Team Win Recovery Project) via Odin.
Repartition (Critical): Use a PIT file to increase the /system partition to at least 1GB. Without this, the 5.1.1 firmware will fail to install due to "Status 7" errors. The Samsung Galaxy S2 (GT-I9100) never received an
Flash Firmware: Boot into TWRP, "Wipe" data/cache, and "Install" the .zip firmware file from an SD card.
GApps: Install a "Pico" or "Nano" Google Apps package specifically for Android 5.1 (ARM architecture) if you want the Play Store. Where to Download
The most reliable source for these files is the XDA Developers Forum for Galaxy S2. Look for "Stable" builds in the "Original Android Development" section. Avoid third-party "firmware update" sites that require surveys, as they often contain malware or incorrect files.
You need Odin3 v3.07 or newer (Windows) to flash a custom recovery first. For Mac users, use Heimdall. Custom ROM ZIP: e
cm-12.1-20160418-UNOFFICIAL-i9100.ziptwrp-3.x.x-x-i9100.tar.tar.md5.Odin3.exe as Administrator.Added!..tar.md5 file you extracted earlier.In the Android enthusiast community, firmware versions are occasionally shortened to major numbers (e.g., 511 = version 5.1.1, 442 = 4.4.2). However, for the GT-I9100, 4.1.2 is not Android 5.1.1 (the S II never received an official Lollipop update). The “511” tag in this specific case is likely a mislabelling from old download repositories where filenames or folders contained “511” as a random identifier, or confusion with later custom ROMs (e.g., CyanogenMod 12.1 – Android 5.1.1). Do not expect Android 5.1.1 features if you download a “511” labeled stock ROM for the GT-I9100 – it will be Jelly Bean 4.1.2.
The Samsung Galaxy S II (GT-I9100) is a legendary smartphone. Launched in 2011, it shipped with Android 2.3 Gingerbread and officially ended its life on Android 4.1.2 Jelly Bean. However, for enthusiasts and budget users, the device is far from dead. Thanks to the aftermarket development community, you can now run Android 5.1.1 Lollipop on this aging hardware.
If you have been searching for the term "gti9100 firmware 511 download upd" , you are likely looking to breathe new life into your old device. This article will explain what this firmware is, where to find safe downloads, how to perform the update, and how to fix common problems.
Important Warning: Flashing custom firmware carries risks, including voiding your warranty (irrelevant for a 2011 phone), bricking your device, or losing data. Proceed at your own risk.
Last Updated: October 2025
Device: Samsung Galaxy S II (GT-I9100)
Target Android Version: 5.1.1 Lollipop
You need a custom recovery like TWRP (Team Win Recovery Project) or CWM (ClockworkMod). For Android 5.1.1, TWRP 2.8.7.0 or higher is recommended.
