WLAN Poller is used to identify if an AP is about to "eat itself" but it is not foolproof and it needs to be run several times in order to catch the file corruption before the AP crashes. Once the AP crashes, WLAN Poller won't be able to recover the AP.
You won't need the file to upgrade.
We did the update yesterday of our WLC and it went fine. We did run WLAN poller from a MAC OSx computer before.
With the config of WLAN poller below it gave the result of none affected APs:
But with the below config the script was never able to finish, it just hanged.
So we went ahead and updated the WLC code anyway, and it went fine.