Unable to upload image on WLC due to AP are stucked in predownloading

[Noovi]

Hi Guys,

i am uploading image on WLC 5520 but getting below error.

This may take some time.
Are you sure you want to start? (y/N) y

Transfer cannot happen because at least one AP is upgrading

later when i saw in 'show ap image all', i observed few AP predownload status is showing as failed but that AP keeps trying predownloaing image and due which i am unable to upload image.

Predownload Predownload Flexconnect
AP Name   Primary Image    Backup Image   Status   Version   Next Retry Time   Retry Count    Predownload
------------------ -------------- -------------- --------------- -------------- ---------------- ------------ --------------
AP02          8.3.150.0          0.0.0.0           Failed    8.10.171.0    03:00:47            3 

Any chance to remove AP from this stucked predownload??

[marce1000]

 - Check if you are not affected by https://www.cisco.com/c/en/us/support/docs/wireless/aironet-700-series-access-points/218447-ios-ap-image-download-fails-due-to-expir.html (https://bst.cisco.com/bugsearch/bug/CSCwd80290) , in that context it could be useful to check on the ap console what is happening (if possible). Or else reboot a problematic AP and check it's status and or try the pre download again , 

 M.

[Leo Laohoo]

Either reboot the offending AP or temporarily assign that AP to a different (or non-existing) VLAN.  

Once the WLC is able to complete the upload, put that AP back to the original VLAN.

[jagan.chowdam]

Have you checked the bug "CSCwd80290" IOS AP image validation certificate failed/expired, causing AP join issues.

https://www.cisco.com/c/en/us/support/docs/wireless/aironet-700-series-access-points/218447-ios-ap-image-download-fails-due-to-expir.html#anc18

If you are, then follow the steps

1. Disable NTP

2. Change the date on the WLC to something before December 4, 2022 but not before November 1, 2022

3. Wait for all of the APs to come up in Registered state with the new image

4. Enable NTP after AP joins the WLC on the new code.

CJ

/*Please rate all useful responses*/

[Gaurav Kansal]

Dear Noovi,

Have you tried "Abort Predownload" option on Wireless > Access Points > Global Configuration page. Please try this option and reply the outcome of this. Hope this will clear the stuck predownload.

Good Luck.

[Rich R]

1. Do what @Leo Laohoo said - shut the AP switchport or put it into an isolated VLAN to stop the AP joining until after you've upgraded.
2. Make sure you're upgrading to 8.10.183.0 or later - refer to field notices below.  You also didn't mention what version you were trying to install?
3. That's a big version jump between 8.3.150.0 and 8.10 code and there's a possibility it just won't work.  You might need to manually upgrade the AP from CLI on console and downloading an image from TFTP server, possibly by starting with an 8.5 image first before upgrading to 8.10.  You didn't mention what model of AP it is?

ps: Abort Predownload won't work because the AP is downloading not pre-downloading.

[Maksym_A]

Hi,

If many points are updated simultaneously, then this is normal controller behavior.
On the access point in the logs you can see:

Controller rejected image download.Maximum concurrent predownload limit has reached
Image_pre-download task delay 528 seconds.
Image download did not start for 30 seconds.
Back-off and retry.

[Rich R]

That's not the same thing as this thread is about @Maksym_A 
There are a number of conditions that cause an AP to endlessly try to download without success - refer to Field Notices below.

There is also a bug which can cause the WLC to lose track of how many APs are downloading so that it thinks there are APs downloading when there aren't: https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvj32563 although that should not affect most 8.10 releases.  On 8.3 (which the original poster was using) you can using the commands mentioned in the bug notes to check and reset the AP download counter.