Inconsistent file permissions. tmp/configCache.php
If you get this error when trying to update Wordfence, please try the following.
1. On the Wordfence diagnostics page, turn on "Disable config caching"
2. Using FTP, remove the file wp-content/plugins/wordfence/tmp/configCache.php
3. Attempt the update again
This message occurred in older versions of Wordfence, and config caching has been replaced with a method that does not use a file. Once you have updated to a newer version, this should not reoccur.