Whilst setting up a new Wordpress install for a site development I found an odd little issue that would only occur in certain circumstances. My current development platform consists of an Apache server on which I create a virtual host for every development site I need. However, rather than setting a DNS entry for each address I just listen to diferent ports. In this particular instance I used the port 59419.
When the install was complete I was presented with the following error at the top of every admin page.
Warning: parse_url(http://10.0.0.1:594191?ver=20091217) [function.parse-url]: Unable to parse URL in \www\wp-includes\script-loader.php on line 542
For some reason Wordpress was adding a "1" to the end of the port number, which was causing the URL to throw a warning message when calling parse_url() as the port number can't be higher than about 65535 (depending on the system). This normally wouldn't cause an issue on most setups, but in this case it increased the port number just high enough to throw this error.
Although the warning is issued on line 542 of wp-includes\script-loader.php, I actually tracked the offending code down to line 438 in the same file. Here it is, along with the comment above it:
// Register "meta" stylesheet for admin colors. All colors-* style sheets should have the same version string. $styles->add( 'colors', true, array(), $colors_version );
The true value is normally a CSS filename, but this one is needed to set some initial conditions for the rest of the admin styles. So when this is appended to the base path it is converted to 1, which is what normally happens when you echo a true boolean value in PHP. To solve this issue I just replaced this true value with a string consisting of a slash.
$styles->add( 'colors', '/', array(), $colors_version );
This has no effect on the functionality of this code. Removing this line completely will cause the admin area to lose all colours and images.
Although this is a very minor bug, it must have caused an issue on someone's system at some point in the past. So I put this fix here in case anyone else has had the same issue.