Can't install plugin via WP Toolkit: destination folder already exists

Symptoms

• WordPress plugin can't be installed

  An error occurred when installing the "wordpress-seo" plugin on the website with the ID 18: Could not install the wordpress-seo plugin on https://example.com website. Please check server logs or contact your server administrator.

• The following error is logged to %plesk_dir%admin\logs\php_error.log 

  Installing the plugin..
  Warning: Destination folder already exists. "C:/Inetpub/vhosts/example.com/wp-content/plugins/wordpress-seo/"
  Plugin installation failed.
  , stderr: No plugins installed.
  {"err_code":true,"err_message":"No plugins installed."}

Cause

A folder with the name used by the plugin installation already exists.

Resolution

1. Log into Plesk

2. Go to Domains > example.com > File Manager

3. Open wp-content/plugins and do either of the following

   • Rename the folder using the option from the three bar menu , or
   • Select the plugin's directory (e.g. wordpress-seo) and press the Remove button

4. Continue with the plugin installation