required-profile-field

function extra_user_profile_fields( $user ) { ?>
<table class="form-table">
<tr>
<th><label for="location"><?php _e("Location:",'valentino'); ?> <span class="description"><?php _e('(required)'); ?></span></label></th>
<td>
<input type="text" name="location" id="location" value="<?php echo esc_attr( get_the_author_meta( 'location', $user->ID ) ); ?>" class="regular-text"  /><br />
<span class="description"><?php _e("Please enter your location.",'valentino'); ?>   </span>
</td>
</tr>
<?php }

add_action( 'personal_options_update', 'save_extra_user_profile_fields' );
add_action( 'edit_user_profile_update', 'save_extra_user_profile_fields' );


add_filter('user_profile_update_errors', 'valentino_check_fields', 10, 3);
function valentino_check_fields($errors, $update, $user) {

  // Use the $_POST variable to check required fields

  if( empty($_POST['location']) )
    // add an error message to the WP_Errors object
    $errors->add( 'location_required',__('Location is required, please add one before saving.') );

  // Add as many checks as you have required fields here

  if( empty( $errors->errors ) ){

    // Save your custom fields here if no errors are found
    // Just skip this if you don't need to do extra work.
    // Fields will save if no errors are found
  }
}