I've been playing with Wordpress as a CMS project recently and came across an interesting "semi-bug(let)" that took ages to resolve, but was rather simple in the end.
A white screen.
Attempting to login to my admin screen after being logged out after a connection dropout gave me a blank screen, nothing on view-source: and no errors in the Apache logfile.
Googling for the issue, I found several posts advising me to clean out my browser cache, clear cookies and check to see if my wp-config.php file ends with a blank line.
None of those fixed it, so I went hunting further and saw people suggesting that one should remove any plugin code -- having a Wordpress installation with heaps of plugins, removing them one-by-one was annoying at best, but some more searching found this neat plugin to resets Wordpress back to it's installation defaults with one click.
(Obviously, if you care about the contents of your blog, or the settings you have crafted for the individual plugins, this isn't for you -- but it helped me out immensely. Kudos to Matt for inventing it.)
Nope -- didn't fix it either.
Removed my theme, restored the default Kubrick theme ...
*shazam*
Fixed.
Put my theme back, logged out, logged back in:
A White Page.
OK, at least I have something to go on, it's a problem with the theme. So I started to poke around further.
It turns out, the functions.php file cannot have spaces in between the functions you define, compare the following code:
<?php
if ( function_exists('register_sidebars') )
register_sidebars(2, array(
'before_widget' => '<li class="widget %2$s">',
'after_widget' => '</li>',
'before_title' => '<h2 class="widgettitle">',
'after_title' => '</h2>',
));
function widget_search() { ?>
<li class="widget widget_search">
<h2 class="widgettitle">Search</h2>
<input type="text" id="searchfield" />
<img id="searchspinner" src="<?php bloginfo('template_url'); ?>/images/ajax-loader.gif" alt="∗" />
<script type="text/javascript">
var search = new Search('searchfield', 'searchspinner');
</script>
</li>
<?php }
if ( function_exists('register_sidebar_widget') )
register_sidebar_widget(__('Search'), 'widget_search');
?>
<?php
function theme_comments($comment, $args, $depth) {
$GLOBALS['comment'] = $comment;
(code edited)
Fails, but:
<?php
if ( function_exists('register_sidebars') )
register_sidebars(2, array(
'before_widget' => '<li class="widget %2$s">',
'after_widget' => '</li>',
'before_title' => '<h2 class="widgettitle">',
'after_title' => '</h2>',
));
function widget_search() { ?>
<li class="widget widget_search">
<h2 class="widgettitle">Search</h2>
<input type="text" id="searchfield" />
<img id="searchspinner" src="<?php bloginfo('template_url'); ?>/images/ajax-loader.gif" alt="∗" />
<script type="text/javascript">
var search = new Search('searchfield', 'searchspinner');
</script>
</li>
<?php }
if ( function_exists('register_sidebar_widget') )
register_sidebar_widget(__('Search'), 'widget_search');
?>
<?php
function theme_comments($comment, $args, $depth) {
$GLOBALS['comment'] = $comment;
(code edited)
Works perfectly.
So where was the problem?
the blank line between the closing ?> in the register_sidebar_widget call and the opening <?php in the theme_comments function.
Undoubtably, your error will occur between a different set of functions, but if you are using a functions.php file in your theme and it begins to fail unexplainedly on you, check the file for blank lines between functions as part of your diagnostics plan.
