Too few erase blocks

Issue: Logfile shows jffs2: Too few erase blocks

Thu Aug 16 07:51:23 2018 user.notice kernel: [ 12.026759] mount_root: jffs2 not ready yet, using temporary tmpfs overlay
Thu Aug 16 07:51:49 2018 kern.err kernel: [ 49.266881] jffs2: Too few erase blocks (3)

Further symptoms: Settings can not be saved / changed settings are lost after reboot

Root cause: Too large firmware. Not enough free space for jffs2 partition (required: >=3 erase blocks).

Solution: No solution except a smaller firmware image. See → low flash for solutions.