Reference documentation is here.
Do not attempt to start a sensor before verifying settings and connection.
Check system status when running into trouble.
Follow the steps below without skipping them.
Even if xDrip+ insists you should start the sensor, do NOT start it before you've setup everything correctly. Hit the back button to get rid of the message until instructed to start the sensor.
Verify your settings⌁
If you haven't yet, check xDrip+ will not be put to sleep (then come back here).
Enter the correct transmitter code, verify it.
Carefully check your settings.
Make them exactly like this:
Native algorithm disabled unless you know why you want it enabled.
With Android versions below 10 disable
With Android versions 10 and above, if you experience disconnections you can try to disable first
Avoid Scanning and eventually also
If you use a Samsung phone with Android 11 and above, you should enable this.
Less Common Settings /
Mind the Bluetooth watchdog ang G5 Bluetooth watchdog with turn off then on your phone Bluetooth, this will lead to a temporary Bluetooth disconnection on all connected devices. You might want to disable this feature if you use AAPS and your bridge/pump doesn't recover automatically Bluetooth connection.
For Samsung phones you must disable
Trust Auto-Connect! If your phone is not a Samsung but loses connection you can try to disable it too.
For Android version 8 and above you can enable
Use Background Scans. If you lose connection, leave it disabled.
Restart your phone to make sure all parameters are being taken into account.
Insert the transmitter in your sensor.
You will not be able to connect xDrip+ if the transmitter is not is not inserted in the sensor.
Make sure the transmitter is successfully connected to xDrip+ monitoring its system status. Do not continue until then.
Once connection is confirmed proceed to start sensor.