After firing this command from your terminal “php bin/magento setup:upgrade" If you get blank screen or your website crash and you get error in your log file, then just follow below steps to solve the issue.
Here the simple steps are
- Delete the “di” folder located in var directory via cpanel or FTP
- Log into your terminal via ssh access and go to your magento root directory
- Run this command to change directory command: “cd bin”
- Then run this command “sudo ./magento setup:di:compile”
- Go back to your magento root directory
- Finally give file/directory permissions through command.
- Clear the cache and check your website is working now.