WordPress currently (this article is from the end of August 2015) does not handle plugin updates very well – if something goes wrong (for example, your account is too low on disk space, and you reach 100%), then it can leave your plugin in an inconsistent state.
Symptoms of your plugin being in an inconsistent state would be any of these:
- That the plugin does not appear on the “Plugins” page in your dashboard (and possibly, when you try to re-install it, you’re told that the directory already exists).
- Or, that after updating an error about a missing file shows on your site, or perhaps just in the dashboard or in the UpdraftPlus log file, mentioning the plugin and a missing file (especially the words “failed to open
stream: No such file or directory”).
- Or (for versions of UpdraftPlus from September 2015 onwards), there’s a dashboard notice telling you so.
The only thing to do in this situation is to remove the plugin, and re-install it. Before re-installing it, check how much free disk space you have – if it’s less than 50Mb, then you may need some more (UpdraftPlus is around 21Mb when unzipped – but WordPress creates a second copy when updating, as well as the downloaded zip file).
If the plugin does not appear on the “Plugins” page in your dashboard, and if re-installing tells you that the directory already exists, then you must use FTP (or the file manager in your web hosting company’s control panel) to remove the plugin. Log in to your web-space via FTP (or file manager), and entirely remove the directory wp-content/plugins/updraftplus.
This article is also very useful for understanding more about how WordPress installs plugins – it’s useful information for all kinds of situations when something goes wrong.