When trying to update to the new 3.8.1 release, I am seeing this error:
Update WordPress Downloading update from https://wordpress.org/wordpress-3.8.1-partial-0.zip… Unpacking the update… The update cannot be installed because we will be unable to copy some files. This is usually due to inconsistent file permissions.: wp-admin/includes/update-core.php Installation Failed
I tried the fix mentioned in this post.
(Author has confirmed that he is not using better-wp-security)
When I tried that fix, however, I get the same problem, except with a different file later in the process. By that point, the file that I had modified has been overwritten, so the hack doesn't work any longer.