Getting 500 Internal Server Error on a remote server only -- works fine locally.

Thanks! In that case, can you make this small edit to the Ruby SDK to enable some additional debugging output? Just add this third line (with set_debug_output) after http is defined in the self.do_http def in the Dropbox module in dropbox_sdk.rb:

def self.do_http(uri, request) # :nodoc:

    http = Net::HTTP.new(uri.host, uri.port)
    http.set_debug_output $stderr

Then please run the failing method again and copy over the resulting output. Be sure to redact secret values (such as the app secret and access token secret, but please keep the keys showing).

Feel free to open an API ticket with it instead if you'd prefer to share privately:

https://www.dropbox.com/developers/contact