Ubuntu – Unable to ‘apt-get dist-upgrade’ due to appstreamcli database error

16.04apt

I have created a USB stick with a persistent Ubuntu 16.04 (release version). I tried a couple of ways, using Startup Disk Creator and MultiSystem, but I get the same end result.

When I boot into the USB and do 'apt-get update', all is well. When I try 'apt-get dist-upgrade' I get:

** (appstreamcli:2761): CRITICAL **: Error while moving old database out of the way. AppStream cache update failed.

The only reference to this error message I can find is https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/1561472 but would appear to be fixed, at least fixed by the time the release version of Ubuntu 16.04.

Aside: I want to test Unity8, which includes installing software. I don't have a spare computer, so I thought a persistent USB would do the trick.

Any takers?

Best Answer

This also happened to me using 16.04.1 live Ubuntu persistent USB stick.

uncledave's solution didn't work at first, but as suggested, changing the rights was the final solution.

Then I've found answer #11 from daniel-gimpelevich for bug 1601971 The following commands helped me repair apt-get update

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/

and

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 this apt-get update ran 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

Note1 Upgrading a live persistent USB stick this way is not suggested it will cause issues if too many packages are installed/upgraded.

Note2 It's a better idea to install Ubuntu directly to the USB stick if you want to use it as a bootable "Swiss Army Knife".

Related Solutions

Ubuntu – Error performing sudo apt update in persistent live boot system (ubuntu 16.04 LTS)

The simple answer is you are abusing the persistence mechanism and you need to stop =)

The somewhat longer answer is persistence uses a COW (copy on write) mechanism - https://en.wikipedia.org/wiki/Copy-on-write

Sorry for the Wikipedia link =)

So the iso (well technically the root files system , squashfs) is a read only file system. This "iso" or root file system can never be changed short or remastering the iso.

Enter the idea of persistence, a mechanism to create an overlay if you will . So if you update your system or make changes, the changes are made to a file (persistence) and not the iso.

This works well for simple tasks such as making adjustments to your interface, customizing the desktop, saving some data, saving wireless passwords.

But the COW system breaks down and you make changes on changes. So you have a base RO file system, and you run sudo apt-update over and over, the COW system is not a database to tack all those changes to changes to changes and eventually fails.

The fix is to either:

Use Persistence sparingly, and make as few changes as possible, perhaps storing user settings, wireless passwords, and installing, one time, some applications. But do not abuse it by treating it as an installed system and try to run sudo apt update && sudo apt upgrade , the COW can not handle multiple changes to hundreds of packages.
Just do a regular install. Probably the best idea as you obviously intend to continue to use Ubuntu.

Hope that answer is not too technical and I hope I did not over simplify the situation too much .

Ubuntu – appstreamcli: AppStream system cache was updated, but problems were found: Metadata files have errors: /var/cache/app-info/xmls/fwupd.xml

This requires a manual edit, due to a bug in a settings file for the fwupd package:

sudo apt install expat
xmlwf /var/cache/app-info/xmls/fwupd.xml
sudo vim /var/cache/app-info/xmls/fwupd.xml

Go to the line number given by xmlwf In my case I got

/var/cache/app-info/xmls/fwupd.xml:268:72: not well-formed (invalid token)

Replace the & character (on the line 268 in my case) with &

Then you can run update again:

sudo apt update

Best Answer

Related Solutions

Ubuntu – Error performing sudo apt update in persistent live boot system (ubuntu 16.04 LTS)

Ubuntu – appstreamcli: AppStream system cache was updated, but problems were found: Metadata files have errors: /var/cache/app-info/xmls/fwupd.xml

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