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Fatal error: Uncaught TypeError: mysqli_close(): Argument #1 ($mysql) must be of type mysqli, null given in C:\xampp\htdocs\mjccorporate.org\android\User-Registration.php:36 Stack trace: #0 C:\xampp\htdocs\mjccorporate.org\android\User-Registration.php(36): mysqli_close(NULL) #1 {main} thrown in C:\xampp\htdocs\mjccorporate.org\android\User-Registration.php on line 36