Indiserver disconnects with error code -1 for exposure with ZWO ASI6200MM Pro

2020-07-24 20:46:29,834 new Message 2020-07-24T20:46:29: [INFO] Taking a 10 seconds frame... 
2020-07-24 20:46:29,836 172.19.0.1:59174 POST /elements/1/cameras/1:startExposure 1.1 202 57 9393
[2020-07-24 20:46:29,836] 172.19.0.1:59174 POST /elements/1/cameras/1:startExposure 1.1 202 57 9393
2020-07-24 20:46:40,939 new Message 2020-07-24T20:46:40: [INFO] Exposure done, downloading image... 
2020-07-24 20:46:41,064 new Message 2020-07-24T20:46:41: [INFO] Download complete. 
2020-07-24 20:46:41,066 new Message 2020-07-24T20:46:41: [WARNING] Telescope focal length is missing. 
2020-07-24 20:46:41,067 new Message 2020-07-24T20:46:41: [WARNING] Telescope aperture is missing. 
INDI server indiserver/7624 disconnected.
2020-07-24 20:46:43,274 Server disconnected (exit code = -1,indiserver:7624)

import requests

url = 'http://localhost:9001/elements/1/cameras/1:startExposure'
data = {'exposure':10}

x = requests.post(url, json = data)

print(x.text)

def newBLOB(self, bp):
        self.logger.info("new BLOB " + bp.name)
        print("name: ", bp.name," size: ", bp.size," format: ", bp.format)
        # get image data
        fits=bp.getblobdata()
        print(type(fits))
        # write image data to BytesIO buffer
        blobfile = io.BytesIO(fits)
        # open a file and save buffer to disk
        with open("%s.fits" % datetime.now(), "wb") as f:
            f.write(blobfile.getvalue())
        blobfile.close()