Error While create REST request for create file

I set the headers like following:
Headers:

accept: application/json;odata=verbose
Content-Type: application/json;odata=verbose
Authorization Bearer xxxxxxxxxxxxxxxxxxxx

{

  "apiUrl":"https://xxx.sharepoint.com",
  "overwrite":"true",
  "folderName":"/Document",
  "fileName":"zxc.txt",
  "filecontent":"abcdedwv",
  "accessToken":"xxxxxxxxxxxxxxxxxxxxxxxxxx"
}

But It returned status: 500 Internal server error ,Please tell what could be the reson for this?