22

Recently, I tried to run the command, sudo apt-get update and got the Temporary failure in name resolution error. But, after that the command proceeded and went on to update. Should I worried about the error. Below is the complete log:

sudo apt-get update
sudo: unable to resolve host {hostname}: Temporary failure in name resolution
Hit:1 http://in.archive.ubuntu.com/ubuntu focal InRelease                                                                                                                                                 
Get:2 http://in.archive.ubuntu.com/ubuntu focal-updates InRelease [114 kB]                                                                                                                                
Get:3 http://security.ubuntu.com/ubuntu focal-security InRelease [114 kB]                                                                                                                                 
Fetched 6,581 kB in 6s (1,180 kB/s)                                       
Reading package lists... Done
muru
  • 207,228
User04
  • 221

7 Answers7

33

It seems likely that your computer's hostname is not configured correctly. There are two files you should check; /etc/hostname contains just your computer's name, and /etc/hosts will have a line that maps the IP address 127.0.1.1 to your hostname. For example, those files might look like:

username@ubuntu ~ $ cat /etc/hostname
ubuntu

username@ubuntu ~ $ cat /etc/hosts
127.0.0.1       localhost
127.0.1.1       ubuntu


The following lines are desirable for IPv6 capable hosts


::1     ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

If you don't have those, try adding them -- keep in mind that a hostname should only consist of letters, numbers, and hyphens -- then reboot and see if you have that error again.

Minneyar
  • 834
8

I have a similar issue. I was trying to renew SSL certificate using: sudo certbot renew I kept on getting the error: Temporary failure in name resolution. “An unexpected error occurred” while issuing certificate bla bla bla. The error means there is a missing, wrongly configured or inactive resolve.conf file.

The fix is simple, you need to restart:

$ sudo systemctl restart systemd-resolved.service

Then check the status of the file with:

$ sudo systemctl status systemd-resolved.service

Then run the renew SSL command

sudo certbot renew

This resolved my issue

Community
  • 1
user1617947
  • 81
2

I fixed it with:

hostnamectl set-hostname hostname.newdomain.local
cocomac
  • 3,824
user15897086
  • 121
  • 1
0

I faced this issue in recent times. Please try to edit your /etc/hosts file by using any editor just as vi or nano after that you will see this line 127.0.0.1 localhost 127.0.1.1 ubuntu remove the line 127.0.1.1 ubuntu and edit it as 127.0.0.1 yourdomain

It is solved my issue; I hope it is also work for you.

anonymous2
  • 4,325
Prem Patil
  • 1
0

I ran into this error when I configured the hostname to include an underscore character (_). This is an invalid hostname, so it was never resolvable in the hosts file. Here's some information on creating a valid hostname:

A hostname can contain a maximum of 255 characters, including the dots. The text string in a hostname must be from ASCII characters. It includes the upper or lower case (A to Z or a to z), digits (0 to 9), the dot symbol (.), and the hyphen symbol (-).

Justin Seaman
  • 1
0

This error occurs when you change the hostname with sudo hostnamectl set-hostname . If you changed your host name with it you also have to add it in the /etc/hosts file.

windowsuser@notwindowsuser:~$ hostname
notwindowsuser

Here my hostname is the name after the @. And I added it here

windowsuser@notwindowsuser:~$ cat /etc/hosts
# This file was automatically generated by WSL. To stop automatic generation of this file, add the following entry to /etc/wsl.conf:
# [network]
# generateHosts = false
127.0.0.1       localhost
127.0.0.1       notwindowsuser # The change occurred here

The following lines are desirable for IPv6 capable hosts


::1     ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
Bemigho
  • 21
0

Check that /etc/nsswitch.conf isn't missing and that it contains the line:

hosts: files dns

Oliver Moran
  • 101
  • 1