When you try to install a plugin and receive a “The package could not be installed. No valid plugins were found.” error, then please follow these steps:
- You have downloaded the complete plugin + documentation files in one zip
- Unzip the file you downloaded first locally
- You will find a XX-plugin.zip file on your local PC
- Upload the XX-plugin.zip via WP-Admin
If this still does not work unzip also the plugin.zip file and upload the files via FTP into your wp-content/ folder.