CM12.1S ROM for Galaxy S2 GT-i9100! [Android 5.1]


Looking for a good Android 5.1 Lollipop ROM for your Galaxy S2 GT-i9100?

Check out the CM12.1S ROM, which is a hybrid of CM12S ROM from OnePlus One and latest Android 5.1.

This ROM features latest CyanogenMod CM12.1 Android 5.1 features along with OnePlus One camera, AudioFX, Screencast (screen recording app), and Hexo theme. I’ve tried many of the latest CM12.1 and Android 5.1/5.1.1 ROMs in the past week but found this ROM to be most stable with everything working out of the box except Netflix video playback.  Also, if you want to know about all of the latest CM12.1 ROM features, check out this video.

Overall, this is a fantastic Lollipop ROM for those of you who want to get your feet wet with Lollipop so definitely check it out this week(end).  I should have an update real soon though on a stable Android 5.1.1 custom ROM.


Download CM12.1S ROM for Galaxy S2 GT-i9100

Download Android 5.1 Gapps (DO NOT USE older Gapp as you will FC!!!)

 For installation, please follow How to Install Android Lollipop ROM on Galaxy S2!

To install, reboot into recovery, make backup ROM, wipe data/factory reset, install ROM, install Gapps, install SuperSU and reboot. (If for some reason you end up in a bootloop, reboot into recovery, go to Advanced Wipe for TWRP or Mounts & Storage for CWM, format/wipe /system, then re-install ROM.)

Credits – XDA <— Please donate to the developer of this ROM or hit Thanks button on XDA if you like it, thx!

Extra MODs:

Missing root?  See How to Enable Root on CM12.1!

Want Flash Player?  See How to Install Flash Player on Android Lollipop!

If you want some awesome audio, check out Viper4Audio FX MOD, which you can install on this ROM to enhance your music 100%.

If you want to run your apps in tablet/hybrid/custom DPI mode, see our Xposed App Settings guide.

Need to run apps that check for root?  Check out How to Run Apps that’s don’t run on rooted Android!

If you want PIE Controls, see our LMT Pie Control guide.


Q: My 3G/4G LTE data is not working!!!
A: See How to Fix 3G/4G LTE data by Manually Setting APN on Android!

Q: I have no Play Store!
A: Make sure you install Gapps zip file in TWRP or CWM Recovery!!!  Download link in this post above.

Q: I have no Root!
A: For CM12.1 ROMs, see How to Enable Root on CM12.1!

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71 Responses

  1. sanjay mehta says:

    to upgrade, i booted first into recovery mode, upgraded the cwm kitkat zip file, then file & lastly the gapps file but now i am stuck with a yellow exclaimation mark with samsung galaxy s2 GT-I9100, & the phone does not boot. what to do ? please help URGENTLY !

    • Alfredo Diaz del Valle says:

      Hey I just did the same and also got stuck with a yellow exclaimation mark with samsung galaxy s2 GT-I9100! Any suggestions plz.

      • Raaj bhere says:

        Go to the recovery mod and wipe data/factory reset.

        • Alfredo Diaz del Valle says:

          Thats the problem it freezes on the boot screen and it doesnt let me pass to the recovery mode!

          • Raaj bhere says:

            You mean stuck on Samsung logo…

            You have to long press home key power key and volume up key to go to the recovery mod.

            • Alfredo Diaz del Valle says:

              Yes, sorry I meant to say that its stuck on the Samsung logo with the yelow triangle. It only lets me go into download mode(long press home key power key and volume down key). It doesn´t respond to Recovery Mode (long press home key power key and volume up key).

              Thanks by the way for your help! I appreciate it!

              • Raaj bhere says:

                You are always welcome bro..!

              • sanjay mehta says:

                solved my problem by booting in download mode, reflashing using odin,
                ensuring the last working ROM file is in place on sdcard, before
                rebooting in recovery mode, & immediately installing the working
                ROM. note, if you don’t reinstall the old working ROM, & try to
                continue booting once in recovery mode, you will be stuck up with the
                same exclamation mark !. now am able to use my mobile with my old ROM.
                not interested in 5.1 immediately atleast…..

    • Raaj bhere says:

      Wipe data/factory reset

  2. ‫ניצן לן‬‎ says:


    When the phone starting the installation, I gut a warning: “No file_contextdetected filesystem ext4 for /dev/block/mmcblk0pg,

    and after that: “Operation not supported on transport endpoint.

    Someone know what that meant ?


  3. Pedro says:

    Does it work on the i777?
    Thanks in advance

  4. Yash Sanghvi says:

    phone gets stuck on CWM recovery when trying to flash the rom help

  5. ‫ניצן לן‬‎ says:

    I installed this CM12.1S ROM on Galaxy I9100 and it looks OK.
    But when I try to open Gmail, I gut the massage: “Unknown issue with google Play services”.

    Can you help me with that ?

    Thanks, Nitsan.

  6. Cosmin Andrei says:

    Google play services keeps crashing! Please do something!!! (I.m using the latest version of G.Apps)

  7. Alfredo Diaz del Valle says:

    Just installed the CM 12.1S and gapss latest version, got stuck with a yellow exclaimation mark with samsung galaxy s2 GT-I9100 no boot. It doesn´t even let me go to recovery mode

  8. Pedro says:

    I have installed it on my GT-I9100. I download the files through my PC because problems arise when downloading with the mobile. It runs quite smooth but from time to time an error message from Gapps appear informing that they stopped. But if you continue it seems not affecting the correct functioning.

  9. Max Hoshou says:

    Same problem with gapps crashing randomly.
    I have also a problem with ringtone not playing through speakers when earphones are connected. Anyone knows how ti fix it?

  10. MEHMET SEMİH Clk says:

    battey life so bad fix please

  11. Monkey D Luffy says:

    I can’t use Google Now launcher on this rom, because Trebuchet is default, As i fix this?

  12. marksauunnviarsson says:


    Is it possible to put this rom on GT-I9105?

  13. zahid khan says:

    Can I update without pc ..


  14. Raaj bhere says:

    Video player is not working..fix it.

  15. Nightvave says:

    Pls provide link to download “install SuperSU”….ASAP
    I still didn’t get ROOT even after following :

  16. mohd hisyam says:

    im already installed this rom…so on ok but my phone getting hot and
    hot while browsing, how to fix it.Camera problem with panorama
    side..home screen some time icon missing when using app in main app. pls
    let me knw how to fix it. Ty

  17. ĶĦălěď Ķäbô says:

    how can i get the twrb recovery mode ?

  18. guest says:

    it is imposible to install this ROM from internal mem or SD card … there is always ext4 problem.

  19. Blaž Veber says:

    SlimLP ROM on XDA Developers. Try it! Android lollipop 5.1.1

  20. Daniel Bernardo says:

    Reformatted internal memory with PIT Master: 8GB/ 8GB
    Also have the random Google Play services crash, camera occasionally stops working and MMS not working (investigating on this).
    This same dev also has a non hybrid CM12.1 with regular updates… considering moving into this one instead.

  21. Daniel Bernardo says:

    Had a unexpected reboot and lost all Google Play installed Apps.
    Found XDA Thread for this ROM:
    Will try update today.

  22. Daniel Bernardo says:

    Had to abandon this ROM in favour of its base CM12.1 build by LysergicAcid.
    The size outgrow the capability to install Google Apps.
    Currently quite happy it the base custom CM12.1 by Lysergic Acid. Smaller and more stable.

  23. matty52 says:

    i new to all this, have rooted my s2 which was easy ish the only problem i have is that all the roms i try wont install from my ex SD card, says failed to mount, so i am stuck with with jellybean 4.1.2 as the roms wont install 🙁

  24. niranjan malinga says:

    I’m getting a Status 7 error.. Please help me..

  25. gronglefink says:

    I had a few issues with doing this.

    I have a GT-i9100. The phone had previously been rooted and I updated the CWM/TWRP to the one that was KitKat compatible (CWM v6.0.5.1).

    I would always to a complete wipe of
    Dalvik Cache

  26. gronglefink says:

    I had a few issues with doing this.

    I have a GT-i9100. The
    phone had previously been rooted and I updated the CWM/TWRP to the one
    that was KitKat compatible (CWM v6.0.5.1).

    I would always wipe everything beforehand, i.e.:
    wipe Dalvik Cache
    wipe data/factory rest
    wipe cache partition
    under “mounts and storage” I would format /storage/sdcard0

    That’s probably overdoing things, but I wanted to be sure that things were “clean.”

    After the above wiping I received different results from changing the order of the install.

    First install order:

    With this install order I ended up with a bootloop showing the android logo. The android logo was animated and appeared to be doing something. Although after 3 hours of this, you know you have a problem.

    Second order:

    With this install order I ended up with a Samsung S 2 that would boot, but there was no prompt to enter in my Google ID and password. I would try and run Google Play Store and it would appear for an instant and then disappear. Under Accounts in Settings there was no option to enter my Google UserID.

    So at the end of it. I got it working by the install order of ROM first and the gapps second and skipped the SuperSU. So that all works, but there is no su access. Which is somewhat problematic.

    Those where my adventures.

  27. Marco Del Gallego says:

    this will not work with the latest 2.4+ version of SuperSU. This version works

  28. Tiago says:

    how we make to install without losing our apps?

    Can you help please

  29. Tiago says:

    SuperSu doesn’t installs binary and with that, titanium backup and others apps that should need root access don’t work.
    Help please

  30. Tiago says:

    “root access possibly lost” WTF is that? Have I lost root in my device?

    • matty52 says:

      go into settings you can turn root back on there cm12.1 turns root off tap build a few times to get devloper and turn on root

  31. Tiago says:

    if I install supersu, it doesn’t work

    if I don’t install supersu, it works.

    What do I make for have supersu? I have already installed with play store but supersu doesn’t work (no access and no update binary)

    Please help, Please, is really important

  32. Robert Bogdiun says:

    is it works with galaxy s2 I9105P ?

  33. akki says:

    hi, the camera app with the gapps has panorama view error. force closes. Any solution to this?

  34. Denis Athens says:

    I live in Greece, installed Lollipop on a galaxy GT-9100 as per instructions but, GPS is not working! Any suggestions, as to how to proceed? I am a novice, so, please, don’t miss any required steps!

  35. Rômulo Areal says:

    Does anyone solved the problem with Netflix app? It’s the only problem I’m having…

  36. Shakeel ahmed khan says:

    I have been trying to install this lately . every time i install i got struck on Samsung logo. i tried everything wiping system and all , that doesn’t worked out …

  37. Nikola says:

    I have big problems with CM. Sometimes when i finish call it just freezes and i cant do anything, only solution get out battery and restart. Same thing happens when i watch videos on chrome. And its not like always, its like 1 in 10 times. Does anyone else have this problem too?

  38. Shakeel ahmed khan says:

    is anybody there ? Reply me please.

  39. Saleh Alsayaad says:

    does not work.
    “signature verification failed”

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