Same here - I cannot complete the update because the plugin says it cannot write to config files and wp-content directory although the permissions should allow it and did so for the previous versions.
Also detects permissions incorrectly - like: says the current permissions are 755 and they should be changed back to 755.
"Either the /(MY PATH)/httpdocs/wp-content directory is not write-able or another caching plugin is installed.This error message will automatically disappear once the change is successfully made."
the directory is writeable, previous versions worked fine, and there are no other cache plugins
I even removed the previous install and did a clean install of W3 Total cache... but with no success.