Hi Rex - you essentially removed the line that set at_least_one_entry=1. Yes, that removes an extra "}" but if you look at the generated script, the linux line specifies no kernel image and the initrd line includes no file. This will result in an unbootable system. linux root=ZFS=rpool/ROOT/ubuntu ro intel_iommu=on iommu=pt quiet splash intel_iommu=on iommu=pt rootdelay=3 zswap.enabled=1 zswap.compressor=lz4 zswap.zpool=z3fold ${vt_handoff} initrd } So, I believe the problem is deeper than a simple syntax error, there is content missing. Additionally, when you look at the debug output you'll see there were other kernels installed which should have gone under a submenu. Content is being truncated or not carried through. This might be a dash problem -- I can't tell. But to remove the extra "}" does not resolve the issue. Thanks, Jeff On Sun, Oct 20, 2019 at 9:35 AM Rex Tsai