If possible, could you share a link to your wordpress and discourse instances? If that’s not possible, please have a look at the /site.json endpoint of your discourse. For example if you go to meta.discourse.org/site.json you’ll see some JSON that includes a categories list. Essentially that error appears if:
- Your Discourse instance returns a non-error response; but
- There’s no
categoriesin your site.json for some reason.
The most likely cause of this is still that described in the topic @Lilly linked. If you could try walking through the steps in this topic and check whether you still have a valid connection to your Discourse: