I am trying to modify the sidebar widgets under Appearance -> Widgets, but whatever I do (just change one option, or remove a widget, etc.), as soon as I press the Update button, on the bottom left it says There was an error. The response is not a valid JSON response.
Upon inspecting the Network tab of the browser DevTools, the request is showing up as v1?_local=user and the request URL is https://host/wp-json/batch/v1?_locale=user with a method of OPTIONS. This request returns a status code 200, but there is no response data – unsure if this could be the issue or not.
What I tried so far (after each point I tried editing the widgets again):
- Updated WordPress to 5.9
- Updated all plugins
- Disabled all plugins
- Switched to a different theme
- Saved changes on the permalinks
- Used a different
.htaccesssuggested by a different website - Checked the Site Health, it does not report any issues with the REST API
Everything else seems to work just fine, I can create/edit posts, pages, etc., but the widget editing keeps failing.
What else can I try to fix this issue?