If you are using zf7363 access points, you can only upgrade to 9.12.
9.13 GA notes:
EoL (End of Life) APs
The following AP models have reached end-of-life (EoL) status and, therefore, are
no longer supported in this release. If your ZoneDirector is currently managing any
of these models, a warning will appear when you attempt to upgrade.
If your ZoneDirector is currently managing any of these models, do NOT upgrade
to this release. ZoneDirector will be unable to manage them.
• 7321
• 7321-U
• 7441
• 7761-CM
• 7762 series
• 7363
• 7343
• 7341
• sc8800-s
• sc8800-s-ac