Recently while working on a WordPress project with Ups Dock, I encountered a weird error where I wasn't able to update or publish a simple post in my local WP admin.
\nIt looked something like this:
\nSometimes the error message would be slightly more helpful: Publishing failed. Error message: The response is not a valid JSON response.
Since the error message had to do with a JSON response, I initially thought it was a Gutenberg or ACF issue. But it turned out this was happening because I was on the https WP admin (i.e. https://project.ups.dock/wp-admin), not the unsecure WP admin (http://project.ups.dock/wp-admin).
\nIt was a CORS error!! I was trying to modify a non-https domain from a https domain. Switching to a non-https WP admin allowed me to publish posts with no problem.
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