Linux kernel maintainer Linus Torvalds has announced a last-minute delay to the release of Linux 4.15, marking the first time a kernel version has needed a ninth release candidate since 2011.

“I really really wanted to just release 4.15 today, but things haven’t calmed down enough for me to feel comfy about it, and Davem [David S. Miller] tells me he still has some networking fixes pending,” Linus explains of the delay, announced on the same day Linux 4.15 was due to go live. “Laura Abbott found and fixed a very subtle boot bug introduced this development cycle only yesterday, and it just didn’t feel right to say that we’re done. So I’m doing an rc9 [ninth release candidate] instead. I don’t particularly like to, but I like it even less releasing something that doesn’t seem baked enough.”

The changes in the ninth release candidate – the first time a kernel version has required so many since Linux 3.1 in 2011, which required ten release candidates before being declared ready for launch – relate largely to architecture updates in the x86, Arm, PowerPC, and MIPS architectures along with some driver and networking plus what Linus describes as “various random misc. fallout” – the latter likely a reference to the patches for the Meltdown and Spectre vulnerabilities which have been causing instability in some systems.

Linux 4.15-rc9 is expected to be the final release candidate before Linux 4.15 launches in full, likely later this week.