How to resolve “Warning: Declaration of Min_DB::connect($server, $username, $password) should be compatible with mysqli::connect($host = NULL, $user = NULL, $password = NULL, $database = NULL, $port = NULL, $socket = NULL) in /var/www/html/adminer-4.2.2/adminer/drivers/mysql.inc.php on line 9” this issue with adminer?

Defalt adminer version i.e. 3.7.x needs php5.x packages to install and is not compatible with php7.x . So, for php7 version download and install adminer’s compatible version i.e. 4.2.x package or zip file.

After installation this package may throw above warning as there is systax difference in drivers of both versions. Just edit

 nano /adminer/drivers/mysql.inc.php

and replace

function connect($server, $username, $password)

with

function connect($host = NULL, $user = NULL, $password = NULL, $database = NULL, $port = NULL, $socket = NULL)

and also set the permissions accordingly , it will solve the issue.