If your site runs through Cloudflare, be aware that Gutenberg currently has an issue with the way their REST API works in Gutenberg.
The Cloudflare WAF (Web Application Firewall) blocks it, and no content created with Gutenberg can be saved.
When you attempt to save your content, you will see the following message in the top left of the editor:
Clicking the Learn More link produces a pop up window with this message:
The 2 links shown are:
I hit the browser’s Back button to get out of this pop up and avoid returning to the Classic Editor.
For the Cloudflare Pro plan:
- Go to Cloudflare > IP Firewall
- Go to the WAF Firewall settings.
- Scroll down to the section for Package: Cloudflare Rule Set and click the Rule Details link on the bottom right.
- Scroll down to the bottom.
- Click directly on the words Cloudflare WordPress to open those settings.
- Use the Next arrow at the bottom to go to page 31-40 to find the WP0025A and WP0025B rules.
- Set those to Disable. Then click the Close button at the bottom.
- Purge the Cloudflare Cache.
I’ll keep you updated on this fix.