How to fix crashing and “No Service” after downgrading 06.15.00 baseband

Several of our users have been reporting with the 06.15.00 downgrade method we posted early this morning. Some people have been having issues getting the to go through(still trying to figure out the cause of this), but others have been successful with the but have been experiencing crashing or "" errors. For those people with crashes or "" try going into Cydia>Manage>Packages and select MobileSubstrate, then go to modify then click "reinstall" on the next page click "Continue Queuing" and then go back to the packages page and find Ultrasn0w and do the same for that except this time hit "Confirm." This will reinstall both Ultrasn0w and MobileSubstrate which has worked as a for a few different people I've talked to with these errors.

  • McValente

    Worked here! Thanks a million, easy and effective. Praise the Lord for the Pros!! :) HugZ

    • JaeM1llz

      Great, thanks for reporting back!

      • Cleveri

        Can you help me i did all of that But while reinstalling it giv eme un error “Could not activate cellular data network” can you help plz?

  • Sitaramp

    It worked! THANK YOU

    • JaeM1llz

      You’re quite welcome 

  • Hatakeliklaisun

    i’m on 3g 4.2.1 and it did not work i’m still on 06.15.00..

    • Jjfeliciadedam

      I have the same problem as you. Ugh i tried everything, I’ve been doing redsn0w baseband updates and there’s no way to downgrade those… or even jailbreak a 4.12.01 — iPhone 4

  • padjo

    it works.. thanks…

  • Joel997744

    haha it work thank you so much :)

  • Tttd


  • Flash ElAhlawy

    MobileSubstate or MobileSubstrate ?????

    • JaeM1llz

      No such thing as MobileSubstate

  • Eric Chung

    It is really working!!! Thanks!!

  • Jjfeliciadedam

    I have a iPhone 4, BB 4.12.01 and I’ve read recently that they’re still trying to come up with something to jailbreak it… I’ve jailbroken my iphone but it’s tethered so it’s choppy, my phone just went out of service 24hrs ago. Cydia crashes, and I’ve also read the only way to unlock it is to call my carrier… it’s BELL… this is bullshit. Fucking iPhones, thought they were supposed to be the best. LOL I’m so upset.

    • JaeM1llz

      You can already perform an untethered jailbreak on iOS 5.1.1 on an iPhone4

  • Daniel_a86

    Tried every possible way. I even forgot about the downgrade that doesn’t worked, I really need my cellphone back.
    I’m happy for those who succeeded. But now I have no GPS or a phone, just a thicker Ipod, it is very frustrating.
    Iphone 3gs New bootrom IOS 5.1.1 untethered JB/BB06.15.00/model MC134/bootloader 6.4_M3S2

    • Daniel_a86

      I’ve flashed to 06.15BB again and re-install mobilesbstrate and ultrasn0w… At least my cellphone is back!!

  • Jack

    Thank you VERY MUCH!!!!!!!

    • JaeM1llz

      You’re welcome!

  • Helgig1

    Thank you so much!! I am truly grateful

  • Pingback: Anonymous

  • Al

    3gs old bb downgrade from 06.15 to 05.13.04 with os511:
    gps works!!! yeahhhh!!! great job!!! jailbreak & unlock works – yeahhh ;-)
    BUT STILL HAVING CRASHES….grrrr. dam….any suggests?

    Thanks a lot!

  • Daniel_a86

    Does anybody why this downgrade method fails for several users?

  • Neilhaj

    i’m on a 3gs (new rom) jailbroken with rocky raccon and i’ve tried 5 times but still can’t downgrade. i got a message saying my phone had already been jailbroken with RR (does this make a difference?)



    • JaeM1llz

      You need to turn the phone off before clicking “jailbreak.”

      • Neilhaj


        i have done this eac time, still nowt?

        • JaeM1llz

          Once the phone is off, click jailbreak and continue following the downgrade tutorial.

          • Neilhaj

            cheers but still nothing, i’ll try waiting for a few more days and see if there are any updates out etc

        • Syed Sayeed

           pwn dfu it then do.. even i had same problem

      • raymond


        • raymond


  • Hatakeliklaisun

    any new updates for downgrading baseband??????

  • Zulfarrez_90

    thanks bro

  • Moosa_vayani

    how to downgrade 3gs baseband when already crashed? after crashed i downgrade it but still no service restart & imie,wifi and bluetooth nil

  • Shmupi

    It worked , had to re-install 
    Ultrasn0w and MobileSubstrate

  • Rik

    Worked for me! Thanks guys.

  • Gevin Prathibha

    restore it to the 5.1.1 and upgrade the baseband to special ipad baseband (NOT IPHONE 4,4S users)after complete goto cydia ->ultrasn0w ->install and respring it u have complete the task

  • Mani

    after downgrade there is no signal no wifi no bluetooth .. what to do after reading the comments below i found how to go to the menu of ultrasnow and mobilesubstrate …but i cant find the re install button me out

  • Blanaru2004

    Thanks !  It works, you’re the best!

  • leocali33

    Hi when I copy the files after the reboot, nothing happen and if I check both files Mobile and Ultrasnow, it disappear from the folder AutoInstall created

  • Misteroldport

    I have spent many hours working on an old iPhone 3GS phone that was jailbroken to the 6.15.00 modem firmware – trying to get it to work on the Straight Talk $45 plan. It would give me the same old errors as everyone else – 10, 20, 10##.

    The ONLY thing that worked was what this post said to do. ONLY THING that works – period. Very good reference!

    1. Redsn0w 0.9.14b2
    2. Jailbreak
    3. Add iPad base
    4. Flash
    5. Re-Jailbreak
    6. Downgrade iPad base & add Cydia
    7. Go to Cydia – Manage – Search and add Mobilesubstrate & Ultrasn0w
    8. Add APN for Straight Talk

    BOOM – perfect, every time. That’s the ONLY method that works. ONLY one. Once again, very good job in doing this post. Best resource available, hands down.

  • ftohaeshil

    its dosent work what i have to do still pore network and sometimes no serves

  • hamdi

    hi i updated my iphone 3gs 4.1 to 6 vervion but after that i stoped in activaion iphone so i cant acces to my phone , please tell my how can i get it back as the same verion or still on version 6 if i can

  • mike

    I had same issue with 3GS 32GB on iOS 4.1 downgrading with redsn0w 0.9.15b3. After the first downgrade shot I got no service, no wifi and no bt. I was also not able to reinstall the packages as described. But I tried again with no sim card installed, selecting the ipsw file of the currently installed iOS and having cydia installation and downgrade selected. This time it was successful.