Fatal errror after updating WordPress 4.7 to PHP 7.x

I am having a similar problem. I have 3 wordpress servers running windows 2012r2, PHP 5.6.29, WordPress 4.7, and MySQL 5.7.17 with NO problems.
I tried to update one server to PHP 7.1 and I get the following error

PHP Fatal error:  Uncaught Error: Call to undefined function mysql_connect() in C:\inetpub\wwwroot\TestWebsite\wp-includes\wp-db.php:1570
Stack trace:
#0 C:\inetpub\wwwroot\TestWebsitep1_njsent\wp-includes\wp-db.php(658): wpdb->db_connect()
#1 C:\inetpub\wwwroot\TestWebsite\wp-includes\load.php(404): wpdb->__construct('MYsql_user', 'MYsqlpassword', 'MYsqldatabase', 'localhost')
#2 C:\inetpub\wwwroot\TestWebsite\wp-settings.php(107): require_wp_db()
#3 C:\inetpub\wwwroot\TestWebsite\wp-config.php(89): require_once('C:\\inetpub\\wwwr...')
#4 C:\inetpub\wwwroot\TestWebsite\wp-load.php(37): require_once('C:\\inetpub\\wwwr...')
#5 C:\inetpub\wwwroot\TestWebsite\wp-blog-header.php(13): require_once('C:\\inetpub\\wwwr...')
#6 C:\inetpub\wwwroot\TestWebsite\index.php(17): require('C:\\inetpub\\wwwr...')
#7 {main}
 thrown in C:\inetpub\wwwroot\TestWebsite\wp-includes\wp-db.php on line 1570

How can I get PHP7 to connect to my MySQL database?
I also tried to setup a new website with just wordpress 4.7 and no plugs and get the same error