aws lex bot api

I'm trying to export my lex bot using aws lexv2 api, I used this api url: https://runtime-v2-lex.us-east-1.amazonaws.com/bot/botname/alias/botaliasname/user/userid/text

H: Content-Type : application/json but I got this error : { "Output": { "__type": "com.amazon.coral.service#UnknownOperationException" }, "Version": "1.0" } any idea how to fix it ?