I have a 8520 and I recently tried to upgrade to 5.0 and the desktop managers keeps telling me that no software updates are required for my device. I currently have the 4.6.1.259. Anybody know why I cant upgrade or how to do it? i have no data plan and i have deleted the vendor file in app loader afer that is there another vendor file somewhere. what are the next steps. thanks for your help.

this will be helpful

How do I upgrade the OS on my BlackBerry? - BlackBerryFAQ

no luck

Actually it wasn't helpful.

The problem is you don't have a data plan. OS 5 will not install EASILY without a data plan. Search or hunt around for threads on how to install OS 5 without a data plan. It can be done, it is just more work.

i have exactly the same problem! we have two blackberry curve 8520 and one has updated to 5 but the other says no update required!!!!

I have had to downgrade to DTM 5.0 and it installed from there for 1 of my 8520, it will accept the update if your are going from 5.0 to a higher 5.0, but if your going from 4.6 to 5.0 then it will give issues with DTM 6.0 saying about the data plan.