Sometimes your router or ISP is the silent culprit.
Once you are back inside your city, take these preventative measures: Simcity Buildit 1100.7 Error
If none of the above work, a clean reinstall is required. Only do this if you are 100% sure your city is backed up to Facebook, Google Play, or Apple Game Center. If you were a guest player, you will lose your city. Sometimes your router or ISP is the silent culprit
SimCity BuildIt uses Coordinated Universal Time (UTC) for events. If your device’s clock is off by even 30 seconds, the handshake fails. the handshake fails.