The popular WordPress plugin WP Super Cache was updated to version 1.5.0 earlier today. Unfortunately our test website became completely inaccessible after updating, and we had to restore the previous version 1.4.9 from our backup.
We haven't had time to investigate in more detail, but judging from comments in the support forum others are experiencing similar issues. So you may want to postpone updating for a day or two until the developer has had time to investigate. Or at least make sure you have a recent backup at hand before you update.
Update July 20
Version 1.5.1 is out and our test WordPress site no longer crashes. However, WP Super Cache appears to be looking for our .htaccess file in the wrong location. This is the correct location on our server:
And this is where WP Super Cache appears to be looking:
Notice the missing "/" in front of
The rewrites that WP Super Cache wants to write to .htaccess appear identical to the old rewrites, and caching seems to work on our test site, so we'll leave it running for now, until 1.5.2 is out.
Update July 21
The plugin author (Automattic) has fixed the missing "/" issue in the code available on Github. A new release that includes the fix is expected sometime next week.
We recommend staying on release 1.4.9 until this is resolved, at least if you use .htaccess-based caching.
Update July 27
Release 1.5.2 came yesterday, but it had a critical uninstall bug and was superseded by a bugfix release 1.5.3 a couple of hours later.
The latest version appears to work correctly, however given the number of bug fix releases over the past week we would suggest waiting a few days more if you are still on 1.4.9 - there does not appear to be any security-related need to update, and cache performance is unchanged.