I was able to boot with both upper and lowercase PARTUUID using:
$ apt-cache policy initramfs-tools initramfs-tools: Installed: 0.122ubuntu6~rc2 Candidate: 0.122ubuntu6~rc2 Version table: *** 0.122ubuntu6~rc2 500 500 http://ppa.launchpad.net/apw/initramfs-tools-test/ubuntu xenial/main arm64 Packages
I was able to boot with both upper and lowercase PARTUUID using:
$ apt-cache policy initramfs-tools ppa.launchpad. net/apw/ initramfs- tools-test/ ubuntu xenial/main arm64 Packages
initramfs-tools:
Installed: 0.122ubuntu6~rc2
Candidate: 0.122ubuntu6~rc2
Version table:
*** 0.122ubuntu6~rc2 500
500 http://