Warning: Undefined variable $conexion in /customers/a/6/b/amscasas.com/httpd.www/secciones_fijas/contacto.php on line 5

Fatal error: Uncaught TypeError: mysqli_query(): Argument #1 ($mysql) must be of type mysqli, null given in /customers/a/6/b/amscasas.com/httpd.www/secciones_fijas/contacto.php:5
Stack trace:
#0 /customers/a/6/b/amscasas.com/httpd.www/secciones_fijas/contacto.php(5): mysqli_query(NULL, 'SELECT * FROM `...')
#1 {main}
  thrown in /customers/a/6/b/amscasas.com/httpd.www/secciones_fijas/contacto.php on line 5