When trying to upgrade PAM, the screen displays the same message for ~20 minutes and stops. It never asks to reboot the appliance and when it stops, there are communication errors until the appliance is rebooted. Once the appliance is rebooted, it still shows the original version.
PAM 3.3.x and above
When an upgrade patch is downloaded from the Support site, it contains two files: a .bin file and a .sha256 file. The .sha256 file contains the checksum of the file. When the patch is uploaded to the GUI, its checksum should match the one in the .sha256 file. If it does not match, then there is an issue with the .bin file.
The .bin file was deleted and downloaded from the Support site again. When the new .bin file was uploaded to PAM, the Checksum value matched the corresponding .sha256 file and the upgrade was successful.