Watermelon Actually now that I think about it, I could test it by trying to sideload the latest open source release, because I'm using security previews. I don't want my phone to be insecure, but at least I won't be downgrading to a lower version with potential issues. I might test this later myself. I'll report back if I do.
Tested on GrapheneOS version 2025122501, trying to sideload update package 2025122500. Fastboot mode before the update showed the active boot slot is ‘b’. Trying to sideload the package gave this message:
ERROR: recovery:
de0u Update package is older than the current build, expected a build newer than timestamp 1766700961 but package has timestamp 1766700960 and downgrade not allowed
…
Installation aborted.
Then I powered off and booted into Fastboot mode again, which showed the boot slot is still ‘b’, and then recovery mode showed the build number is still 2025122501.
Security preview releases are made together with the open source releases and the GrapheneOS team decided to make them like this (artificially increment the timestamp by 1). But older versions would undoubtedly have an older timestamp.
Thread can be marked as solved.