I had created the file 'word.docs' under the root folder.
Request the api v2 method get_preview with the path for this file return 400 error.
request details :
headers :
"Dropbox-API-Arg" : {"path": "/word.docs"}
"Authorization" : "Bearer my_securiy_token"
"Content-Type" : "application/json"
endpoint : "https://content.dropboxapi.com/2/files/get_preview"
method : "POST"
response : system.HttpResponse[Status=Bad Request, StatusCode=400]