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Nightscout Troubleshooting

Overall third party services

APPLIES TO: DIY Nightscout

Before troubleshooting

Check the services you're using.


Carelink US:

Carelink non-US:






Dedicated page is here.


Dedicated page is here.


Boot Error - Unable to connect to Mongo

Database Full
Reports slow loading or timeout

Look at this dedicated page.

Nightscout page doesn't open

  • With Heroku check here.

No data in Nightscout

Make sure your Nightscout time zone is correct.

Dexcom data not showing

See this dedicated page.


CareLink with mmconnect data source stopped functioning for most.
Remove the mmconnect plugin from ENABLE if you use Heroku.
This probably applies to other providers too.

First verify you can see your BG in Clarity.

If data is present open Heroku and check you app didn't fall asleep.

A sleeping app was due to your Heroku free plan: a Basic plan makes the app never sleep.

Another reason for a sleeping app can be due to a failure to obtain data from Dexcom Share, check the logs to understand the reasons.

UpTime Robot

Using an uptime robot with a bad password, or other issues originating from Nightscout can lead to a locked account (Dexcom) or Heroku addresses ban. This is not a recommended solution as it might generate a global Heroku IP blacklist lock that could propagate to all other users. If you use Nightscout, uploading data in the cloud or even just having a browser or an app downloading data should be enough to keep your app awake.

Error code instead of a BG value

Nightscout implements Dexcom error codes as listed below:

Code Corresponding error
?SN Sensor not active
?MD Minimal deviation
?NA No antenna
?NC Sensor not calibrated
?CD Counts deviation
?AD Absolute deviation
??? Power deviation
?RF Bad RF

Data timing issues

Basal is shifted in time

  • Check the time zone is correct for your currently active profile in your Nightscout Profile editor.

Data in the future

  • Check you don't have data in the future with the Admin tools. Remove them if existing.

  • If this isn't working, or shows no future data, check in your database for Atlas see here

Basal / IOB / COB missing after DST

  • Setup again your time zone in profile editor (authenticate and save).

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