I upgraded to WordPress 2.7.1 on one of my test blogs a few days ago using the new automatic upgrade feature. The upgrade went quickly and smoothly and everything worked afterwards, so that was good.

Tonight, I got round to upgrading my other test blogs and they didn’t go well at all.

Initially on 2 of them I got as far as “Downloading update from http://wordpress.org/wordpress-2.7.1.zip” and that was all; it just sat there doing nothing. OK, so I looked on the forums and saw a suggestion that it might be plugin related, so I disabled all the plugins on one of the blogs, this then got to the next stage “Unpacking the core update” and sat there doing nothing. Hmm, this was strange it worked on the first blog. I tried the update on my last test blog and this worked automatically in seconds. The mystery deepens!

Then I had a thought, back in July, when I was working on the problem with Firestats, I found a resolution by adding a line to my .htaccess file:

AddType x-mapp-php5 .php

This causes php pages to processed by my host 1and1 using PHP 5 instead of PHP 4. Looking at the test blogs that had worked, both had this line in the .htaccess file. Ah, could it be this simple?

I downloaded a copy of the .htaccess file from one of the failing blogs and wasn’t happy to find that WordPress (I guess) had reset it to the default file with only the WordPress rewrite section. Anyway, I added my redirects back in and added the line for PHP 5 and uploaded it.

The automatic update then worked fine. I did the same for the other failing test blog, which also had a default .htaccess file (I’m glad I keep copies) and that also worked. So it looks like the automatic upgrade works with PHP 5 and not with PHP 4