If you are trying to upload any file or plugin on your WordPress website and showing this message “To perform the requested action, WordPress needs to access your web server. Please enter your FTP credentials to proceed. If you do not remember your credentials, you should contact your web host.”
It means your WordPress website doesn’t have sufficient permission to perform this action. To fix the problem you need to run a command in your server, just login your Linux server and enter below given command. If you have changed the root folder name then enter that URL at the place of (/var/www/html/).
chown -Rf www-data.www-data /var/www/html/