HTTP resources are not allowed, must be updated or removed

You are receiving this error because somewhere in your product images, listing templates, or product descriptions, eBay detected insecure HTTP links. 

To resolve the error:

1. First, please check if your Magento site is using SSL and has a valid certificate installed.

2. If you are using a custom description template for your listings, make sure it does not contain any links, like links to images, in HTTP format.

3. And if you publish your Magento Product descriptions on eBay, confirm that it uses only HTTPS and not HTTP.