Plus, we encountered this message when running the following query:

$ curl '<http://localhost:9000/sql>' \
>   -H 'Connection: keep-alive' \
>   -H 'Accept: text/plain, */*; q=0.01' \
>   -H 'X-Requested-With: XMLHttpRequest' \
>   -H 'User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.138 Safari/537.36' \
>   -H 'Content-Type: application/json; charset=UTF-8' \
>   -H 'Origin: <http://localhost:9000>' \
>   -H 'Sec-Fetch-Site: same-origin' \
>   -H 'Sec-Fetch-Mode: cors' \
>   -H 'Sec-Fetch-Dest: empty' \
>   -H 'Referer: <http://localhost:9000/query>' \
>   -H 'Accept-Language: en-US,en;q=0.9' \
>   --data-binary '{"sql":"select count(*) from meetupRsvp limit 10","trace":false}' \
>   --compressed
{"code":500,"error":"Could not initialize class org.apache.pinot.common.function.FunctionRegistry"}

which may be due to https://github.com/apache/incubator-pinot/pull/5440