If you used WordPress before Gutenberg was released and have since upgraded, you have content that wasn’t created with Gutenberg on a site that uses it. WordPress gives you a couple of different ways to manage that content. Here, we’ll examine both.
The Classic Block
By default, any content you created in what is now known as the Classic Editor appears in a special Gutenberg block called the Classic block. Complete with the toolbar buttons present in the WordPress 4 editor, the Classic block allows you to edit your old content with the same interface you used to create it.
Any posts or pages you created in WordPress 4 with the classic editor will show the entire post in a Classic block. You can add paragraphs, images, and any other content to Classic block content just as you could in WordPress 4. All of the content will remain in one block. Since the Classic block is a standard Gutenberg block, you can even add other blocks above and below the Classic block content.
Split content into multiple blocks
Instead of using the Classic block, you can convert the content you’ve created to Gutenberg blocks. To do so, click the three dots on the top-right corner of the block and click “Convert to Blocks.” WordPress will then convert the content you’ve created into multiple Gutenberg blocks — images will convert to Image blocks, each paragraph will become its own Paragraph block, and so forth — as if you had created the post in Gutenberg originally.
If you’re familiar with Gutenberg and wish to edit your previous content in Gutenberg natively, splitting your content into multiple blocks is a good option. If you’re new to Gutenberg and still lean toward the classic interface, you may wish to edit with the Classic block instead, or you might wish to convert your old content to Gutenberg blocks to help you learn how to use the editor. Either way, WordPress gives you multiple options for managing old content, and both options are available for all of your posts and pages you created before Gutenberg.