Access Points unable to Join Wireless Controller

[Jameztee]

My access points are unable to Join the Wireless controller. It looks like the following:

Anyone have an idea how to fix this? Please help....

[Ambuj M]

there can be many reasons, you should provide more information like WLC SW, HW version, AP model, AP logs, debugs etc

anyways go through this link, this has potential reasons why AP wont join controller, you can investigate following the process in the documentation and let the community know what you find, there is a good change you will find the problem and fix it using this documentation

https://www.cisco.com/c/en/us/support/docs/wireless/5500-series-wireless-controllers/119286-lap-notjoin-wlc-tshoot.html

[Jameztee]

Thank you, this is very helpful.

[balaji.bandi]

As asked valid questions, what is WLC Model and Code running, what Model of the AP.

In addition to that, is this AP joined to WLC before ? 

Do you have any other AP join WLC ?

can you connect the Console cable to AP and check what is wrong - by rebooting the AP ?

is the Port up on the Switch side and got enough power to AP ?

[srimal99 · Accepted solution]

@Jameztee  as @balaji.bandi  always good practice to post WLC mode and code version along with ap model.

Community help guide :
https://community.cisco.com/t5/security-knowledge-base/how-to-ask-the-community-for-help/ta-p/3704356

[Rich R]

And it goes without saying that you should make sure your software version is up to date as per the TAC recommended link below.  Currently older models like 2504, 5508, 8510 should be running 8.5.182.12 (link below) and newer models like 3504, 5520, 8540 should be running 8.10.196.0.  Also check against the Compatibility Matrix (link below) for the AP models you're using.