Unable to attach AP's to 5508 7.5.102.0 controller

Question

Initially the controller was running 7.0 with no issues. 1131 AP’s and 1200 series AP's. Additional 1602 AP’s installed and old 1200’s removed (unsupported beyond 7.0.x). Upgraded the controller to 7.5 and no AP’s can join the controller. The 1131’s appear to attach and reboot and stick in downloading mode but the 1602’s never appear to join. I can see DHCP addresses being picked up by AP’s from Monitor stats and CDP. Had to roll-back to 7.0 but had to disable interfaces on all the 1131's attached switchports before the controller would allow me to reboot as it kept stating a message along the lines "cannot complete as AP's are downloading".
Please find attached files. Hopefully trying again next week so any feedback would be appreciated
Thanks

Answer 1

Rasika thanks for your response. the reason I installed 7.5 was that we have deployed it on new installs and not had issues. Unfortunately all installs involve 2602 AP's and I labbed it today again with 2602 AP's on a 2504 and it worked out of the box. I will peruse the links you have provided
I did not load the FUS as it appears to have already been installed
Manufacturer's Name.............................. Cisco Systems Inc.
Product Name..................................... Cisco Controller
Product Version.................................. 7.5.102.0
Bootloader Version............................... 1.0.16
Field Recovery Image Version..................... 7.0.112.21
Firmware Version................................. FPGA 1.7, Env 1.8, USB console 2.2
Manufacturer's Name.............................. Cisco Systems Inc.
Product Name..................................... Cisco Controller
Product Version.................................. 7.5.102.0
Bootloader Version............................... 1.0.16
Field Recovery Image Version..................... 7.0.112.21
Firmware Version................................. FPGA 1.7, Env 1.8, USB console 2.2