The following error message may happen from time to time when attempting to load new software version in Palo Alto Firewall or Panorama :
Preloading into software manager
Error: Image File Authentication Error
Failed to load into software manager. Please retry.
Post processing failed. Please retry
PanOS always do software image integrity check after downloading the file and will return this error in case of mismatch.
This usually resolve by clicking the “Check Now” button (at the bottom left corner) of the Software menu under either the Device tab if you are working directly on a firewall or under the Panorama tab and then hit the Download link again.
If working with CLI, just download again the image from Palo Alto support portal, make sure to check the file signature, upload again on the device and carry on again with the “request software add…” command.