I've performed 256MB and 1GB installs on our ConnectCore 6UL SBC Pros (we have one of each board at the moment) using the instructions at https://www.digi.com/resources/documentation/digidocs/embedded/dey/3.0/cc6ul/yocto-gs_t_program-fw (I used the ConnectCore 6UL SBC Pro .zip file for both).
The 256MB board install went well but the 1GB board installation failed with error message:
"ERROR: Could not mount 'update' partition, volume not found"
Here's the tail messages snippet before rebooting:
ubi2: VID header offset: 2048 (aligned 2048), data offset: 4096
ubi2: good PEBs: 3576, bad PEBs: 0, corrupted PEBs: 0
ubi2: user volume: 0, internal volumes: 1, max. volumes count: 128
ubi2: max/mean erase counter: 2/1, WL threshold: 4096, image sequence number: 4084596699
ubi2: available PEBs: 3410, total reserved PEBs: 166, PEBs reserved for bad PEB handling: 160
ubi2: background thread "ubi_bgt2d" started, PID 186
ERROR: Could not mount 'update' partition, volume not found
ubi2: detaching mtd6
ubi2: mtd6 is detached
rmdir: '/mnt/update': No such file or directory
[RECOVERY] Starting recovery...
[RECOVERY] [ERROR] No command found
[RECOVERY] The system will now reboot in 10 seconds
Is it possible that the update partition is NOT created/included in the 1GB u-boot-ccimx6ulsbc1GB.imx file?