Client with the currently selected authenticator does not support any combination of challenges that will satisfy the CA.

lets encrypt has one security vulnerability so changed command for generating https certificates

Solution :

sudo certbot --authenticator webroot --installer apache

Now it will ask the domain name to install certificates for it. Follow the instructions and you can install certificates successfully.

Note :
Now this issue has been fixed. Update lets encrypt and use regular commands.

s3cmd - 400 Bad Request

ERROR: S3 error: 400 (Bad Request):

Solution :
Use latest version of s3cmd
https://sourceforge.net/projects/s3tools/files/s3cmd/

mod_qos(004): failed to create mutex (ACT)(/var/tmp/K564968484.mod_qos): No space left on device

Solution :
Apache cannot be started because of this error, it means you have installed and enabled qos module in apache to avoid ddos attack. Now apache is crashed automatically and you are not able to start it.

Disable qos module

sudo a2dismod qos

Restart apache2