Troubleshooting Nightscout

Before troubleshooting

  1. Check your email (maybe you missed an important announcement)

  2. Check your internet provider / SIM credit (can all devices browse internet?)

  3. Try another browser/computer (if building your Nightscout site)

Overall third party services

Check the services you’re using are available


Check here:

Dexcom US account
Dexcom non-US account

Carelink US account
Carelink non-US account




MongoDB Atlas




Application crashed

Not knowing if it’s a permanent issue, first try to restart it…


Follow these instructions.


Search your issue there.

There’s nothing here, yet can be due to billing issues.

An Application error means Heroku crashed. Restart it and check database size.


Issues during database creation look there.

The usual reason for failure at build time is a bad connection string (Atlas).

If you encounter a Boot Error - Unable to connect to Mongo it might be due to a Database Full


Mind you can’t deploy Railway if you just created a new GitHub account.

Nothing there is usually because you forgot to subscribe to a Developer plan.

Else go there. troubleshooting is complex if you didn’t save your fly.toml configuration. Check in your local clone of the cgm-remote-monitor project. If you can’t find it, recover it first.

Try to redeploy your app.

Once done, issues are most probably due to your fly.toml contents or variables.

Other issues


Reports slow loading or timeout

No data in Nightscout

Check your uploader is configured correctly.

Make sure your Nightscout time zone is correct.

If you use a DIY closed loop system make sure it’s setup correctly.

Dexcom data not showing

See this dedicated page.

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 (Atlas see here)

Basal / IOB / COB missing after DST

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

Error code instead of a BG value

Nightscout implements Dexcom error codes as listed below:


Corresponding error


Sensor not active


Minimal deviation


No antenna


Sensor not calibrated


Counts deviation


Absolute deviation


Power deviation


Bad RF