this is my environment wlc 8520 with release 8.2.166, i receive the following error in GUI
Blocked:Cannot view/modify the controller configuration while standby wlc is rebooting. Please try after a few minutes.
this happened to someone ??
I've had this issue on a 5508 Controller before
I had to force a reboot of the WLC via command line.
CLI Command is " reset system both"
Note this will reboot both WLCs. you can also try just rebooting the secondary
CLI Command is "reset system peer"
I had this before and had to disconnect the redundancy port between the two which ensured the secondary WLC came up successfully and ultimately then had to rebuild the primary WLC from fresh again because it would never sync config.
The same issue occurred a few months later and I ended up replacing the WLC through TAC/RMA.