Using gps with raspberry pi

Hello! I have a GPS USB dongle that I’m trying to use with my Raspberry Pi 3. I tried it out first using a regular Raspbian image and it seemed to work out fine, but I’m having some trouble getting it to work in my container running a debian stretch base image.

I installed the gpsd libraries and added the DBUS_SYSTEM_BUS_ADDRESS environment variable in my Dockerfile. When I run the command ‘cat /dev/ttyACM0’ I can see all the incoming NMEA strings, so I know the GPS is sending data correctly. However, when I try to pull the data through a python script, I get the error messages in the screenshot.

I would really appreciate any help!