Regretfully, the update does not fix the headers and footers that were corrupted already. What it does is it avoids the issue from Pro 2.4.7 onwards. That might be the case with Global Blocks also.
With that said, it would be best that you restore from a working backup of your site, update to Pro 2.4.7 and then update WordPress.
There is a manually way to get them back, but if you are comfortable with editing your database directly.
- Backup your site.
- Locate the IDs for the headers or footers you are trying to recover. You can do this by opening them in their respective builder. The address bar will include a number which is the ID.
- In your wp_posts table, find the row with the ID is equal to your header ID. When you find it you'll see that the
post_type column should be
cs_footer and you the content is JSON.
- Open the
- Remove any instances of rel="noopener noreferrer". This is the string WordPress added. Because it includes quotes it is breaking the JSON.
If the issue's still happening after you have followed my advice, please give us WordPress Admin and FTP or cPanel access in a Secure Note