This is the kind of thing that happens out of nowhere when you’re in the middle of finishing off something simple, and sends you into a rage shouting “What the fucking hell…this is just bizarre!” and so on, until you finally fix it by fiddling about intuitively, and then just move on. For once, professional discipline compels me to record the problem and its solution, partly for my own benefit but also to help others avoid the drastic solutions offered in several places on the web.
After working primarily in Django for the last while I had to do some WordPress work yesterday, implementing SEO improvements to one of our e-commerce client’s web site. I added a function to functions.php and got everything working nicely, but then I went to /wp-admin only to find a blank screen, with no error messages. Neither could I find anything in the server error logs. I could get to /wp-login.php and seemingly log in succesfilly, but then the same thing would happen – I couldn’t get in to the back end, even though the public site was working just fine.
Most of the proposed and unsurprisingly successful fixes I found in blogs and on the WordPress support forums involved re-installing WordPress, but one suggestion stood out: delete any blank lines at the end of your functions.php file. I’m in the habit of adding extra lines at the bottom of a file to give me more space to work in my text editor, so this looked promising. And it worked.
I don’t know why.