Unable to set feature images in WP 5.5

[rhisflow]

Since upgrading to WordPress 5.5, I am no longer able to set a feature image.

I've tried this on different sites which run on completely different hosting servers, always the same issue.

As you can see from the screen shot, the "set feature image" button simply remains inactive.

Also, the usual image information on the right, once an image has been selected, is missing.

[philetaylor]

Logged in as an AUTHOR, the ajax call responds with

{
    "code": "rest_forbidden_context",
    "message": "Sorry, you are not allowed to edit this post.",
    "data": {
        "status": 403
    }
}

I can replicate this.

[SergeyBiryukov]

Hi there, welcome to Trac! Thanks for the report. Just noting that I could not reproduce the issue on a clean install.

I'm sorry to hear you are having issues with your website since the latest update, but this topic is best discussed on the ​support forums or directly with the developer of your theme or website.

Before heading there to create a post though, I recommend reading through the following list of potential issues with 5.5: ​https://wordpress.org/support/topic/read-this-first-wordpress-5-5-master-list/

The most likely issue is that a plugin on your site is running old JavaScript code. Could you try installing and activating this plugin: ​https://wordpress.org/plugins/enable-jquery-migrate-helper/.

This will confirm that there is JavaScript on your site that needs to be updated to follow more modern jQuery practices. You can leave the plugin active for the time being, but the breaking code will need to be updated before the next step of the Upgrading jQuery in Core roadmap.

If this does not fix the issue, feel free to create a support topic.

[rhisflow]

Just a quick update what I've discovered so far troubleshooting this issue:

1) On one site where this happened, simply deactivating and then reactivating all plugins did the trick.

2) On another site, deactivating and then reactivating one plugin at a time indicated that the plugin which is causing the issue is the "All In One WP Security & Firewall" plugin, so I will raise the issue in the support forum there.