This is just a quick post on an issue I found while testing the open-source WordPress blogging software (www.wordpress.org).
It seems quite a few people over the years have asked for help (mainly on the WordPress forums) to fix a particular JavaScript error which causes their WordPress administration system to break, but it seems that after researching this issue myself (as I also was struck down by this JavaScript oddity) that there were NO useful answers or resolutions.
The error in question was as follows:
'jQuery' is undefined
It also would appear to be a very simple issue to fix.
The problem relates to two JavaScript files which fail to upload completely.
I discovered the following files were 0kb in size on my server and uploading them again fixed all the issues that were affecting the WordPress administration system:
wp-includes/js/jquery/jquery.js wp-includes/js/jquery/jquery.schedule.js
Hope this helps anyone else who experiences this issue (as it appears quite a few do suffer from it).