My WordPress update to Version 2.6.5 with FileZilla client 126.96.36.199 failed somehow because quite a lot sub-folders in wp-includes did not transfer.
This made the visual editor disappear or not working.
Clearing the Cache of Firefox doesn’t elp in that case of course.
I started comparing deep sub-folders manually and transfering the files with folders by ftp one by one.
Finally, if you have more than one site to maintain, that’s to much!
I found a recent post in Filezilla Forum saying:
it’s a bug with 188.8.131.52 – try switching to a nightly until next release.
nightly builts you find here: http://filezilla-project.org/nightly.php
That solved my problem by using i586-mingw32msvc for my windows machine. Now I can transfer the wp-includes folder with all sub-folders to the server.
The missing sub-folders wp-includes/ js/ tinymce/ plugins/ wpeditimage and also crop, jquery, scriptaculous, swfupload and thickbox with their subfolders are now in place and WordPress is working as before!
WordPress update FileZilla