Error creating directory wp-content/mu-plugins when define( 'FS_METHOD', 'ftpext' );

[viewpnt]

Feature request/bug description

The plugin throws an error when trying to activate the "Solve a problem" mode and define( 'FS_METHOD', 'ftpext' ); in wp-config.php

Screenshots

In the webserver logs appears the following message:

"PHP message: PHP Warning:  ftp_mkdir(): /site_path/www/wp-content/mu-plugins: No such file or directory in /site_path/www/wp-admin/includes/class-wp-filesystem-ftpext.php on line 538"

In the ftp logs appears the following message:

127.0.0.1 UNKNOWN example.com [01/Jun/2020:13:13:12 +0000] "MKD /site_path/www/wp-content/mu-plugins" 550 -
127.0.0.1 UNKNOWN example.com [01/Jun/2020:13:16:44 +0000] "MKD /site_path/www/wp-content/mu-plugins" 550 -

Posible cause of the error...

The plugin is not honoring the following settings, and is trying to create the mu-plugins dir in an invalid path via ftp. Somehow it appends the whole path to the website, which is invalid.

define( 'FTP_BASE', './' );
define( 'FTP_CONTENT_DIR', 'wp-content/' );
define( 'FTP_PLUGIN_DIR', 'wp-content/plugins/' );