YukiWhen I upgraded to WordPress 5.0.3, I lost the ability to save drafts, preview drafts, and post. Installing the Classic Editor Plugin allowed me to save drafts and post, but I still couldn’t preview drafts.
As I mentioned in this support thread, I tried all the major recommended fixes, including:
- clearing the cache (in caching plugin and in browser)
- re-saving permalinks
- disabling all plugins through Troubleshooting Mode
- checking to make sure REST API was unaffected
- using the default Twenty Nineteen theme
- checking to make sure my URLs were the same
- updating all themes and plugins
Nothing worked. I kept getting a 404 every time I tried to preview a post.
This is what finally solved the problem:
While my URLs were the same, they were not using HTTPS, only HTTP. As soon as I added the “s” to both URLs and logged back in, the problem was eliminated. Now I can save and preview drafts and post using either the new block editor or the Classic Editor!
Praise God for such a simple fix!
I was using HTTPS from DreamHost to secure my site and access it, but it wasn’t agreeing with the unsecured HTTP URLs in my WordPress admin settings (Settings > General).
If you’re having this same issue, try checking those things! Hopefully it may be a solution for you too.
Other threads covering similar issues:
- https://wordpress.org/support/topic/publishing-fail-after-update-to-wordpress-5-0
- https://wordpress.org/support/topic/read-this-first-wordpress-5-0-master-list/
- https://wordpress.org/support/topic/just-updated-to-wordpress-5-0-1-but-its-giving-errors/
- https://wordpress.org/support/topic/after-update-5-0-problems-with-writing-posts/
- https://wordpress.org/support/topic/unable-to-save-after-wp-5-0-upgrade/
- https://wordpress.org/support/topic/updating-failed-warning-on-autosave/