You should use the access details that were used during the installation. What FTP details did you use during update?

Are those FTP details you used for Oxwall site installation? Make sure you use proper port.

yes, I can do it first, and suddenly can no longer

What error do you receive? Where do you receive it? Attach a screenshot and provide us with more information.

I have this same issue.  My ftp account I use has full permissions.  Tested this and proven.
I have also checked in the server and I do think I have ownership of the files but cannot work out if it is a system permission with apache or my ftp server. (I dont use hosting, I have it on a linux server, no cpanel.  just ssh!)

It doesn't affect me much as I can access the files directly but it would b e nice to have it working perfect.

I usually get the error when I try to load "new" plugins, do updates on plugins or core updates.  (or plugin deletions)
Anything that uses the ftp panel within the admin section.

its same problem :(

Quote from Adhy Musaad its same problem :(

did you fix it im having the same problem it won't log in

Make sure all files on your server are allowed for writing by the FTP user that you are using.