apt doesn’t support architecture i386

After adding facebook hhvm repository on Ubuntu 16.04, i get following error when running “apt update” command.

root@backup:~# apt-get update
Get:1 http://security.ubuntu.com/ubuntu xenial-security InRelease [102 kB]
Hit:2 http://us.archive.ubuntu.com/ubuntu xenial InRelease                                                                                                       
Get:3 http://us.archive.ubuntu.com/ubuntu xenial-updates InRelease [102 kB]                                                                                      
Hit:4 http://ftp.osuosl.org/pub/mariadb/repo/10.1/ubuntu xenial InRelease                                                                                        
Ign:5 http://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/3.4 InRelease                                                                                        
Get:6 http://us.archive.ubuntu.com/ubuntu xenial-backports InRelease [102 kB]                                                                                    
Hit:7 http://ppa.launchpad.net/ondrej/php/ubuntu xenial InRelease                   
Hit:8 http://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/3.4 Release             
Ign:10 https://pkg.jenkins.io/debian-stable binary/ InRelease
Hit:11 https://download.docker.com/linux/ubuntu xenial InRelease
Hit:12 https://pkg.jenkins.io/debian-stable binary/ Release
Get:13 https://dl.hhvm.com/ubuntu xenial InRelease [2,411 B]
Get:15 https://dl.hhvm.com/ubuntu xenial/main amd64 Packages [2,244 B]
Fetched 311 kB in 1s (283 kB/s)
Reading package lists... Done
N: Skipping acquire of configured file 'main/binary-i386/Packages' as repository 'https://dl.hhvm.com/ubuntu xenial InRelease' doesn't support architecture 'i386'
root@backup:~#

This is fixed by editing

vi /etc/apt/sources.list

Find

deb https://dl.hhvm.com/ubuntu xenial main

Replace with

deb [arch=amd64] https://dl.hhvm.com/ubuntu xenial main