What value / how many blocks to increase rootfs size on a RPI 4


I’m trying to increase the rootfs A & B partitions of a RPi4. By default it’s ~128MB / 289044 blocks.
I tried to double it (578088 blocks) but didn’t work. The Pi’s bootloader complains that it doesn’t find any firmware and since the fwup.conf file mentions:

The Raspberry Pi is incredibly picky on the partition sizes and in ways that
I don’t understand. Test changes one at a time to make sure that they boot.
(Sizes are in 512 byte blocks)

I was wondering if someone had some correct values to increase the rootfs size?

Thanks in advance for your help.
Best regards

I did some more tests and i wonder whether the issue i had was not actually coming from balena, not correctly writing my firmware on the eMMC because even my previous build using 289044 were failing afterward.

I ultimately tried with this value 409626 and used the Raspberry Pi Imager to flash my eMMC and this time it worked…