[FreeBSD] zfs: out of temporary buffer space

system: FreeBSD v13.0-p7

reason: the bootloader is broken (e.g. after update)

solution: reinstall the bootloader(s) to your boot disk(s)

example: zroot (2-disk zfs-mirror with GPT partition tables)

download a bootable FreeBSD-Image
(e.g. FreeBSD-13.0-RELEASE-amd64-memstick.img)
copy the image-file to a USB-stick (attention: all data on the stick will be erased)
dd if=<download-folder>/FreeBSD-13.0-RELEASE-amd64-memstick.img of=/dev/<usbstick-device-file>
boot from the USB-stick and select “console”
(notice: the memstick-image is able to boot in BIOS or in UEFI mode)
find out the devicenames and boot partition number from your boot-disks
gpart show
(the partition named “freebsd-boot” is the boot partition on every disk)
reinstall the pMBR and GPT ZFS bootloader (for every booting disk)
gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i <boot-partition-number> <devicename>
(e.g. gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1 ada0)
(e.g. gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1 ada1)
reboot