You will see a progress bar. If it freezes at Receiving image... , your FTP server is blocking passive mode. Allow ports 50000-51000 on your FTP server firewall.
Click the "Download" link next to the .aes file (e.g., AIR-CT2500-K9-8-5-182-7.aes ). You will receive a standard binary file. Verify the MD5 checksum provided on the website against your downloaded file. cisco wlc 2504 firmware download work
The most stable final release for the 2504 is generally in the 8.5.x train (e.g., 8.5.182.0). You will see a progress bar
Cisco has officially announced that AireOS 8.10 is the last supported train for the 2504. There will be 8.12 or 8.14 releases for this platform. Allow ports 50000-51000 on your FTP server firewall
If you are upgrading from a very old version (pre-7.0), ensure your paper licenses have been converted to the electronic format. 📊 WLC 2504 Technical Specs Feature Max Access Points Max Clients Throughput Final Software Train
A common mistake: Upgrading WLC firmware but not the AP image. The WLC will automatically serve the new AP image to joining APs, but this takes time.