A PHP Error was encountered

Severity: 8192

Message: md5(): Passing null to parameter #1 ($string) of type string is deprecated

Filename: controllers/LoginController.php

Line Number: 36

Backtrace:

File: /home/veter/public_html/testingcp4/application/controllers/LoginController.php
Line: 36
Function: md5

File: /home/veter/public_html/testingcp4/index.php
Line: 315
Function: require_once

{"success":false,"error":"no clinica"}