This week I have been updating lots of WordPress installations.  Some of the updates replace versions of WordPress from as early as 2007 (pretty static sites) and there are a few things I’ve learned from the pain of upgrading a WordPress.

1. WordPress Plugins are not supported by their developers forever.  On one blog I’d used a flickr third party plugin, a plugin which has long ago died.  Because it had died, it helped crash the WordPress upgrade as it did not work after the new code was installed. The impact result was  a few hours lost trying to find a replacement plugin, and sifting through hundreds of photo’s which had lost all of their associated data information – Lesson here: try and use Plugins which look like they have an active development community that are going to build on them and support them in the future. Plugins which have very little reviews, appear to be installed by only a few people often appear to die and cause grief later.  Research the third party plugin really well and always think ‘what would I do if this plugin did not work in the future, and what impact will it have on my site’.
2. If you hack the core code, keep notes of what you are hacking.  Due to me hacking the code all those years ago, and because I did not keep notes of what I’d hacked…. I ended up breaking WordPress again. Hacking the code is a necessary evil in WordPress.  Not everything you do with it, or want to be able to do with it can be done by a Plugin, and often involves searching Google for a hack. Hacks will come back to haunt you unless you document them very well. Create a text file of what you have done to hack the code, and bury the text file in a readme file on your server, also send yourself an email of what you did, you’ll be pleased you did.
3. I always forget to do it, but before doing the software upgrade you must deactivate the existing plugins and then activate them again after the installation has completed.  Check each plugin one by one after switching them on.  It would be lovely if WordPress said on the upgrade page ‘Don’t forget to deactivate your Plugins!’
4. Delete the plugins you don’t use.  When you setup WordPress you’ll try out all sorts of Plugins.  Most will be deactivated straight away when you realise you don’t need them, but you’ll probably not delete them off the server.  Delete them off the server straight away!  When you come to do the WordPress upgrade life will be easier as you’ll only have the plugins installed that you use rather than a mix of plugins used and unused.  This caught me out yet again.