Hello,
the error still exists. It looks like a general problem with Azure.
After the private message to Yutong I got a free support. The support first gave me general information on how to set up Bing Custom Search. After we adjusted various settings together, it still didn't work. But he didn't know what to do with the error message either.
His assumption was that the free plan was the problem. I then activated the paid plan and the custom search worked again immediately. This was from April 12 to May 22. Since today, without changing anything, it has stopped working again.
The same error message is displayed: Unable to execute your query. Ensure that a valid subscription key has been set up for your instance.
So it's probably not the free or paid plan but another problem?
Can anyone help? Many thanks in advance.