i'm going to upgrade a pair of WLC with a very old software image. Since this situation requires several intermediate upgrades, I was wondering if I can disable the distribution ports at the begining of the upgrade and then enable them at the end, in order to upgrade the access point just once. Can this procedure create some trouble?
Read the release notes carefully - I recall reading something that stated you should let the AP's upgrade to each version level as you upgrade the controller.
From the 184.108.40.206 release notes:
When you upgrade the controller to an intermediate software release, wait until all of the access points joined to the controller are upgraded to the intermediate release before you install the 220.127.116.11 software. In large networks, it can take some time to download the software on each access point.