Webhooks get error

when i post a trigger url,it was got an error response.
{“actions”:{},“links”:{“self”:“"},“message”:"Error unmarshalling request body in Execute handler: invalid character ‘%’ looking for beginning of value”,“status”:“Server Error”,“statusCode”:500,“type”:“error”}.
so, what should i do?

I cannot reproduce your error. To make sure it’s not something in your code can you go to the Terminal and do a
curl -v -X POST '<url>'
Make sure you put the URL inside of quotes

Thanks for your reply.
The server was worked and response correctly by using curl command,the error was happened when i using a web form to post the trigger url and also the java code,like below.
web form:

java code: