Since RIM blocked OS upgrade for users who doesn't have a shiny and working BB data plan, I was looking a long time for a guide on how to work around this block. Many complicated guides are on the net, but this worked for me (no source provided, it's bits and pieces from wherever...): - do a full backup of your data! best using Desktop Manager - go to c:\Program Files (x86)\Common Files\Research In Motion\AppLoader\ and delete "vendor.xml" file - in this directory, type (in command line) "loader /nojvm" - before that, you have to have a new OS installed in you system, see the leaked OS blog posts everywhere, or just google for desired version - follow the instructions :) This lil' how to is not THE way to do it, but it certainly worked for me, now my 8900 found a second breath. EDIT: OS version 5.x is making me troubles on my BB 8900. Huge battery drain, 1 - 2 days after OS was installed. Battery went dead from fully charged after 3 hours of non-extensive use. Nobody seems to be reporting this, so I have either something wrong with my BB or I did some ugly things to OS with CrackMem, I have no idea, but I wasn't able to fix it so I'm reverting back to 4.6.1 :(