error: ext4_allocate_best_fit_partial: failed to allocate 742 blocks, out of space?

I hope this reply doesn’t come too late for you, but I ran into the same problem, in my case:

error: ext4_allocate_best_fit_partial: failed to allocate 1579 blocks, out of space?

I solved the problem by increasing the root filesystem partition size from 48 (MB) to 96. You should be OK by only increasing to 64 or fewer MB, since you’re only shy by 13 blocks.

Make the change by running

make menuconfig
--> "Target Images"
-->"Root filesystem partition size (in MB)"

I’m building a pretty large/complete install for my ODROID-U2 with 2 GB RAM and 64 GB eMMC flash, a “big” system for OpenWRT, so probably similar to your x86 system in that regard.

https://forum.openwrt.org/viewtopic.php?id=57078