I have WordPress version 4.9 and Book Review version 2.3.9, have created an API key with Google, and set it up with country code “Denmark” and the correct API key in the plugin.
However on the Google API dashboard, every attempt to fetch book info results in an error code 403. That is not a very helpful error code, and I can’t seem to find any other place to look up a more specific error.
First, open the DevTools, click on the Network tab, and then enter an ISBN as per usual and click the “Get Book Info” button. Filter on “admin-ajax” and click on the row that is making a request to get the book details (it will likely be the last one). Please take screenshots of both the Headers and Preview tabs. For example, here is the Preview tab for a request made on my site – https://cloudup.com/iEa5ppvb1Mv