The earliest recollection of this bug is traced back to PAN-OS 10.1.0 - February 19, 2025.
There is a known issue where M-100 appliances are able to download and install a PAN-OS 10.0 release image even though the M-100 appliance is no longer supported after PAN-OS 9.1. (Refer to the hardware end-of-life dates .)
For more information:
https://docs.paloaltonetworks.com/pan-os/10-1/pan-os-release-notes/pan-os-10-1-0-known-and-addressed-issues/pan-os-10-1-0-known-issues
https://docs.paloaltonetworks.com/pan-os/10-1/pan-os-release-notes/pan-os-10-1-1-known-and-addressed-issues/pan-os-10-1-1-known-issues
https://docs.paloaltonetworks.com/pan-os/10-1/pan-os-release-notes/pan-os-10-1-10-known-and-addressed-issues/pan-os-10-1-10-known-issues
https://docs.paloaltonetworks.com/pan-os/10-1/pan-os-release-notes/pan-os-10-1-11-known-and-addressed-issues/pan-os-10-1-11-known-issues
https://docs.paloaltonetworks.com/pan-os/10-1/pan-os-release-notes/pan-os-10-1-12-known-and-addressed-issues/pan-os-10-1-12-known-issues
https://docs.paloaltonetworks.com/pan-os/10-1/pan-os-release-notes/pan-os-10-1-13-known-and-addressed-issues/pan-os-10-1-13-known-issues
https://docs.paloaltonetworks.com/pan-os/10-1/pan-os-release-notes/pan-os-10-1-14-known-and-addressed-issues/pan-os-10-1-14-known-issues
https://docs.paloaltonetworks.com/pan-os/10-1/pan-os-release-notes/pan-os-10-1-2-known-and-addressed-issues/pan-os-10-1-2-known-issues
https://docs.paloaltonetworks.com/pan-os/10-1/pan-os-release-notes/pan-os-10-1-3-known-and-addressed-issues/pan-os-10-1-3-known-issues
https://docs.paloaltonetworks.com/pan-os/10-1/pan-os-release-notes/pan-os-10-1-4-known-and-addressed-issues/pan-os-10-1-4-known-issues
https://docs.paloaltonetworks.com/pan-os/10-1/pan-os-release-notes/pan-os-10-1-5-known-and-addressed-issues/pan-os-10-1-5-known-issues
https://docs.paloaltonetworks.com/pan-os/10-1/pan-os-release-notes/pan-os-10-1-6-known-and-addressed-issues/pan-os-10-1-6-known-issues
https://docs.paloaltonetworks.com/pan-os/10-1/pan-os-release-notes/pan-os-10-1-7-known-and-addressed-issues/pan-os-10-1-7-known-issues
https://docs.paloaltonetworks.com/pan-os/10-1/pan-os-release-notes/pan-os-10-1-8-known-and-addressed-issues/pan-os-10-1-8-known-issues
https://docs.paloaltonetworks.com/pan-os/10-1/pan-os-release-notes/pan-os-10-1-9-known-and-addressed-issues/pan-os-10-1-9-known-issues
