Today, when I attempted to update the Ubuntu system to install the latest patches, the system hanged infinitely at the sudo apt-get update command. This appears to be a bug, but nonetheless, system patching is our priority and this is the workaround, till it gets fixed. To type the commands below, open a linux terminal window.
The computer just displayed the “Reading package lists” and only consumes CPU power. I pressed Ctrl-C to exit the process, the following error is displayed. After a few retries, the below error displayed.
** (appstreamcli:6416): WARNING **: Exception: Unable to get write lock on /var/cache/app-info/xapian/default: already locked
After probing the process list and the Internet, found that appstreamcli was misbehaving.
To prevent this error, firstly stop the update from hanging infinitely:
$ ps -fael | grep "appstream" <enter>
0 R root 5130 1 99 85 5 - 36202 - 10:42 ? 00:25:11 appstreamcli refresh
The process ID 5130 is the reason for the hang. To resolve, do following:
$ kill -9 5130 <enter>
$ sudo /bin/rm -rf /var/cache/app-info/xapian/default <enter>
$ sudo rm -vf /var/lib/apt/lists/* <enter>
Now try to update the system using:
$ sudo apt-get clean <enter>
$ sudo apt-get update <enter>
$ sudo apt-get dist-upgrade <enter>
It no longer displays the error.
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