Signal Failed response error

[Daggle2410]

Hi, when i try to post a new contact or anything else, throws back this response:
{
"corr_id": 0,
"message": "Singal Failed",
"status": "0"
}

my body is
{"mobile_number":"+34 6978 20083","emulator_name":"pixel_1"}
And app.py screen console logs this:
('Unsupported field kind during encoding', [None, '\r', 'emulator_name'], u'pixel_1')
127.0.0.1 - - [18/Aug/2019 18:01:33] "POST /api/v0.1/add_new_contact HTTP/1.1" 400 -