Fatal error:

As per WordPress recommendation i updated my php version 7.2 to 7.3. but after that My admin page not opening any more , showing 2 fetal errors. when my website is opening fine.

this error is like:

1.

Fatal error: Uncaught Error: Call to undefined function mysql_connect() in /home/public_html/wp-includes/wp-db.php:1673 Stack trace: #0 /home/public_html/wp-includes/wp-db.php(632): wpdb->db_connect() #1 /home/public_html/wp-includes/load.php(425): wpdb->__construct(‘gamers_wp857’, ‘.28XpSG8[7’, ‘gamers_wp857’, ‘localhost’) #2 /home/public_html/wp-settings.php(116): require_wp_db() #3 /home/public_html/wp-config.php(94): require_once(‘/home/…’) #4 /home/public_html/wp-load.php(37): require_once(‘/home/…’) #5 /home/public_html/wp-admin/admin.php(34): require_once(‘/home/…’) #6 /home/public_html/wp-admin/index.php(10): require_once(‘/home/…’) #7 {main} thrown in /home/public_html/wp-includes/wp-db.php on line 1673

2.

Fatal error: Uncaught Error: Call to undefined function wp_kses_normalize_entities() in /home/public_html/wp-includes/formatting.php:4305 Stack trace: #0 /home/public_html/wp-includes/class-wp-fatal-error-handler.php(190): esc_url(‘https://wordpre…’) #1 /home/public_html/wp-includes/class-wp-fatal-error-handler.php(147): WP_Fatal_Error_Handler->display_default_error_template(Array, false) #2 /home/public_html/wp-includes/class-wp-fatal-error-handler.php(52): WP_Fatal_Error_Handler->display_error_template(Array, false) #3 [internal function]: WP_Fatal_Error_Handler->handle() #4 {main} thrown in /home/public_html/wp-includes/formatting.php on line 4305

Please help me with this.