You should use 4.0 on all new sites you install WP All Import on. If you are installing WP All Import\u00a0for the first time on a WordPress installation, use WP All Import 4.0.<\/p>\n
You do not have to upgrade your existing sites.\u00a0Upgrading is optional.<\/strong><\/p>\n There are no known security issues in the latest 3.x release.<\/p>\n If we find out about a security issue \u00a0in 3.x down the road, we will alert you via e-mail. As long as you didn't unsubscribe to our e-mails, you'll be notified if there is a security issue in 3.x that requires an upgrade to 4.x. One note about security: 4.0 has enhanced security for uploaded\/imported files. In 3.x, these files can be publicly accessible if someone is able to guess the URL to the file - just like any other file stored in your \/wp-content\/ folder. In 4.0, we added a feature that\u00a0randomizes the directory names the files are stored in, making it much less likely that someone\u00a0would be able to guess.<\/p>\n Technical support will continue to be provided to 3.x users.\u00a0<\/strong>We are happy to continue answering questions about how to use 3.x. If you need a bug fix though, you'll probably have to upgrade to 4.0, unless we opt to release a patch for 3.x - which we will only do for significant bugs.<\/p>\n