Starting pure-ftpd: 421 Unable to switch capabilities: Operation not permitted [FAILED]
At first I thought there was a wrong setting in pure-ftpd, I even copied the configuration of the CWP that was established but it was still an error. Finally I explored via Google and found a little enlightenment. The initial diagnosis is because the installed pure-FTPD is not compatible with the host kernel. Please note that my host uses proxmox version 4.2.7. The guest uses LXC.
So troubleshooting pure-FTPD error 421 is twofold:
Re-compile pure-ftpd, by adding -without capabilities. But in my opinion this is not practical because not necessarily our manual settings match the default CWP
With proxmox update. Now I choose this second method and succeed. The method is very easy
Edit sources list:
vi /etc/apt/sources.list.d/pve-enterprise.list
deb https://enterprise.proxmox.com/debian jessie pve-enterprise
Love comment to be inactive, then add
deb http://download.proxmox.com/debian jessie pve-no-subscription
(because we use the free version)
Clean the repo first with:
apt-get clean all
Next upgrade the OS
apt-get update & apt-get upgrade & apt-get dist-upgrade -y
When it’s finished, then restart
reboot
Finished
Source : https://fatamorghana.wordpress.com/2016/10/07/atasi-pure-ftpd-error-421-operation-not-permitted-cwp/