As part of my recent investigations in the new Gutenberg editor for WordPress I came across a cheeky little error that had me stumped for a while.

Now, I saw this issue whilst running on a local VVV setup, that I’d created solely for this Gutenberg investigations, and as such it was running on an nginx server. I had also not tweaked the default permalinks settings.
Some digging later I pulled out this github issue, and that lead me to the solution workaround here.
Solution
To get it working, all you have to do is set a more fancy permalink structure, such as http://local.wordpress.dev/sample-post/.
Further Info
It seems the issue is to do with PUT request support in the default nginx config, and the way the WordPress REST API works out-of-the-box. If you want more info, follow that trac ticket above.
I hope to be writing more on my Adventures in Gutenberg, especially my work on adding support for it to the Widgets on Pages plugin.
Thanks for this.
In my specific case, I had a function in a plugin that has get_terms / get_the_terms filters. That function is used to display tags with commas in them (https://www.saotn.org/display-commas-wordpress-tags/), but throws a PHP notice when there aren’t any (“Trying to get property of non-object in”).
Disabling this function in my plugin resolved the “Updating failed” notice in Gutenberg.
Unbelievable. I been waiting for the final rollout and hoping that WordPress will this nuisance error. But till date nothing happened. They should have listened to the existing users before official rollout.
Personally i feel, they should let us switch easily between old and new editor. Not everybody likes this fancy new editor.
Robin.
THANK YOU!!!