title_attribute Error

Hi.

I’ve recently been playing around with WordPress – Most notably, the theme.

Unfortunately, I now seem to be getting this error and cannot come to a conclusion about why this would be happening.

The error is:

Fatal error: Call to undefined function the_title_attribute() in /…/…./…./nintendoeverything.com/htdocs/wp-content
/themes/default/single.php on line 13

The code of single.php is the following:

<?php get_header(); ?>

	<div id="content" class="widecolumn">

	<?php if (have_posts()) : while (have_posts()) : the_post(); ?>

		<div class="navigation">
			<div class="alignleft"><?php previous_post_link('&laquo; %link') ?></div>
			<div class="alignright"><?php next_post_link('%link &raquo;') ?></div>
		</div>

		<div class="post" id="post-<?php the_ID(); ?>">
			<h2><a href="<?php echo get_permalink() ?>" rel="bookmark" title="Permanent Link: <?php the_title_attribute(); ?>"><?php the_title(); ?></a></h2>

			<div class="entry">
				<?php the_content('<p class="serif">Read the rest of this entry &raquo;
'); ?>

				<?php wp_link_pages(array('before' => '<strong>Pages:</strong> ', 'after' => '
', 'next_or_number' => 'number')); ?>
				<?php the_tags( 'Tags: ', ', ', '
'); ?>

				<p class="postmetadata alt">
					<small>
						This entry was posted
						<?php /* This is commented, because it requires a little adjusting sometimes.
							You'll need to download this plugin, and follow the instructions:
							https://binarybonsai.com/archives/2004/08/17/time-since-plugin/ */
							/* $entry_datetime = abs(strtotime($post->post_date) - (60*120)); echo time_since($entry_datetime); echo ' ago'; */ ?>
						on <?php the_time('l, F jS, Y') ?> at <?php the_time() ?>
						and is filed under <?php the_category(', ') ?>.
						You can follow any responses to this entry through the <?php comments_rss_link('RSS 2.0'); ?> feed.

						<?php if (('open' == $post-> comment_status) && ('open' == $post->ping_status)) {
							// Both Comments and Pings are open ?>
							You can <a href="#respond">leave a response</a>, or <a href="<?php trackback_url(); ?>" rel="trackback">trackback</a> from your own site.

						<?php } elseif (!('open' == $post-> comment_status) && ('open' == $post->ping_status)) {
							// Only Pings are Open ?>
							Responses are currently closed, but you can <a href="<?php trackback_url(); ?> " rel="trackback">trackback</a> from your own site.

						<?php } elseif (('open' == $post-> comment_status) && !('open' == $post->ping_status)) {
							// Comments are open, Pings are not ?>
							You can skip to the end and leave a response. Pinging is currently not allowed.

						<?php } elseif (!('open' == $post-> comment_status) && !('open' == $post->ping_status)) {
							// Neither Comments, nor Pings are open ?>
							Both comments and pings are currently closed.

						<?php } edit_post_link('Edit this entry.','',''); ?>

					</small>

			</div>
		</div>

	<?php comments_template(); ?>

	<?php endwhile; else: ?>

		Sorry, no posts matched your criteria.

<?php endif; ?>

	</div>

<?php get_footer(); ?>