Gutenberg
This is a test post with the new ‘Gutenberg’ editor in WordPress. The last time I tried to use it was about a month ago and couldn’t even attach the image to the post I was trying to make, I ended up starting again with the regular editor just to be able to complete the post.
After some initial trials I seemed to have discovered at least partial cause to the image upload issues.. now why I was not seeing the issue in the classic editor last time I have no idea, as the cause (configuration on my nginx load balancer) should have resulted in the same error.