Ubuntu 18.04 Linux Kernel Update Causes Boot Delays Of 4 Minutes Or More On Some Systems

A Linux Kernel bug found in a recent Ubuntu 18.04 update is causing very slow boot times (of around 4 minutes or even more) on some systems.

The kernel image that caused the issue (version 4.15.0-24) was released as an update to Ubuntu 18.04 on July 4th, and was already removed from the repository archives at the time I'm posting this article.

A fix for this issue was already released, but the updated package is currently only available in the Ubuntu 18.04 proposed repositories - hopefully it will make it into the main repositories soon.

An user mentions that booting to previous kernels apparently doesn't solve this, though that is probably a different issue.

Until the package containing the fix is promoted from the Proposed repository, if you're affected by this bug (which seems to be entropy-related) you can speed up the boot process by "wiggling the mouse (or a finger on the touchpad) or hitting the shift or ctrl key during boot to make the system generate entropy a bit faster", mentioned Oliver Grawert in a Google+ reply.

This bug does not affect all systems. In fact,  I'm running this kernel right now and I'm not noticing any increased boot times on my Ubuntu 18.04 desktop:


  1. I had same problem on linuxmint 19 with 4.15.0-24, 4.15.0-20 is OK.

  2. You can move mouse or increase entropy in system.

    sudo apt install haveged

  3. sudo apt install rng-tools

    rng-tools installs the rngd daemon which will feed the kernel number generator from HW entropy sources, such as HW random number generators from Intel and AMD CPUs.

  4. On my wife's laptop we decreased the wait time to a couple seconds by using tunefs to run fsck at every bootup,

    example for /dev/hda1 -c 1 makes it scan at every boot

    sudo tune2fs -c 1 /dev/hda1

  5. I have this exact issue with ANY kernel above 4.15.0-20. I tried over a dozen different versions higher and ONLY 4.15.0-20 works straight away. So I seriously doubt its an issue with just 4.15.0-24, at least on my machine.


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