Alex,
Did you notice page 57 of the 6.1.2.7 release notes? When your RAP's are RAP5, then you first need to flash the backup firmware of the RAP5 from the latest 5.0.4.x release; otherwise the RAP5's will not reconnect after the upgrade.
You did not tell the RAP type, but this may be the issue when they are RAP5's.
Upgrading With RAP-5s and RAP-5WNs
If you have completed the first upgrade hop to the latest ArubaOS 5.0.4.x version, and your WLAN includes
RAP-5/RAP-5WN, do not proceed until completing the following process. Once complete, proceed to step 21
on page 57.
1. Check the provisioning image version on your RAP-5/RAP-5WN Access Points by executing the
following command:
show ap image version
2. If the Flash (Provisioning/Backup) Image Version String shows the letters “rn” for example as 3.3.2.11-
rn-3.0, note down those AP names and IP addresses.
3. For each of the RAP-5/RAP-5WN noted in the step-ii, upgrade the provisioning image on the backup flash
partition by executing the following command:
apflash ap-name <Name_of_RAP> backup-partition
The RAP-5/RAP-5WN will reboot to complete the provisioning image upgrade.
4. When all the RAP-5/RAP-5WN with a 3.3.2.x-based RN provisioning image have successfully upgraded,
verify that the provisioning image by executing the following command:
show ap image version
The Flash (Provisioning/Backup) Image Version String should now show for example 5.0.3.3 and not
contain the letters “rn”.
5. If you omit the above process or fail to complete the Flash (Provisioning/Backup) Image upgrade to
5.0.4.x and the RAP-5/RAP-5WN was reset to factory defaults, the RAP will not be able to connect to the
controller running 6.1.2.x and upgrade its production software image.