This question is an exact duplicate of:

When I run 'sudo apt-get update' the response I get is 'AppStream cache update failed.' Have read through all of the questions that may already have your answer and none of them are even in the ballpark of the question I am asking.Two hours ago wiped my hard drive clean and reinstalled ubuntu 16.04.1. The very next thing I did was run 'sudo apt-get update', which failed. Don't see how I can express this plainer or be more specific.

marked as duplicate by karel, Community Aug 30 '18 at 3:34

This question was marked as an exact duplicate of an existing question.

  • If you refresh the AppStream does that help? sudo appstreamcli refresh --force --verbose – Terrance Aug 30 '18 at 2:58

This also happened to me using 16.04.1 live Ubuntu persistent USB stick. The below solution should help.

sudo chmod -R a+rX,u+w /var/cache/app-info/xapian/default

How did I guess that 755 is the right mask? The difference between

ls -ld /var/cache/app-info/xapian drwxr-xr-x 1 root root 4096 Nov 19 20:35 /var/cache/app-info/xapian/

ls -ld /var/cache/app-info/xapian/default drw-r--r-- 2 root root 4096 Jul 19 20:54 /var/cache/app-info/xapian/default

After that, sudo apt-get update should work fine:

sudo apt-get update Hit:1 http://archive.ubuntu.com/ubuntu xenial InRelease Get:2 http://security.ubuntu.com/ubuntu xenial-security InRelease [94.5 kB] Get:3 http://archive.ubuntu.com/ubuntu xenial-updates InRelease [95.7 kB]
Fetched 190 kB in 0s (312 kB/s)
Reading package lists... Done

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