All data missing from midnight

I see it every now-and-then with my Venu2 and it's been happening since I got the watch in September.
I see a blank gap from Midnight to about 2AM in all the charts EXCEPT the sleep graph which shows sleep stages for that period.

I contacted Garmin Support, but like you - Nothing.....I guess they can't be bothered with problem that must have been created during some software update. And since it seems to be across different watches, maybe it's Connect - I don't know.

The response from Garmin support:

"I have referred this to the team, but we have no outstanding reports of this behaviour on the device or Connect in general.

The most likely explanation of heart rate dropout when it consistently happens overnight and not outside of your configured sleep window in contact interruption of the on-board heart rate monitor from the wrist during sleep. 

You will likely therefore, find other users that have experienced similar issues to yourself, and the same can be found for any electrical device and potential issue, but these do only make up a very small minority of users, and very few of these turn out to be genuine faults.  As such, whilst regrettably faults can occur, as they can on any electrical device, there are no known faults with these, which can cause this."

This is the last time I buy a Garmin device.

8697643 said:

This is a very commonly reported issue and there seems to never be a solution for it.

It is commonly reported? I'm visiting this forum every day and don't recall seeing reports about this issue and can't find any posts when I search for missing data in the way you describe it.

Do you see this issue every night or is to working some nights and more or less other nights? Intermittent errors are the hardest to find and fix since they can't reliably be reproduced and therefore not verified if they are fixed to 100%.

If you suspect the sync to be the issue then you should see the data stored on the watch. See if you can find out which file HR data is stored in and verify that data exists when Garmin Connect doesn't show it.

Can you see the 'Related' panel on the right of this post?

Also see this forum post: Bug? Midnight till wakeup, Missing all sleep data when syncing.

Also see this forum post: No HR data after midnight

Also check this Reddit post: Anyone else frequently missing data at midnight?


Also check this Reddit post: No data after midnight


Also check this Reddit post: Stress Missing from Midnight to Wakeup


I can keep going with this. There's hundreds more out there...

e7andy said:

Do you see this issue every night or is to working some nights and more or less other nights? Intermittent errors are the hardest to find and fix since they can't reliably be reproduced and therefore not verified if they are fixed to 100%.

If you suspect the sync to be the issue then you should see the data stored on the watch. See if you can find out which file HR data is stored in and verify that data exists when Garmin Connect doesn't show it.

It is most nights, but not all.

I will try to examine data on the watch, but I would expect Garmin support to be a bit more responsive in solving these issues and not making me turn hacker to diagnose their bugs.

8697643 said:

I would expect Garmin support to be a bit more responsive

In your place, I would contact the vendor or Garmin again and request a replacement watch. Assuming your watch is still covered by the warranty.

Otherwise if you want to try tracking it down yourself, then I can imagine a few reasons why the data is missing:

• (very unlikely) Battery Saver kicking in at midnight - either because you enabled Battery Saver during sleep, and have set the Bed Time to midnight. I wrote 'unlikely', because you would be aware of it, and it would have to be the same every night
• (very unlikely) It cannot detect your HR, for example because the bloodflow is restricted (laying on the arm, peripheral vasoconstriction due to cold temp, or because of sleep apnea / snoring), or because a too loose fit. I wrote 'unlikely' because there is no reason it would always happen at midnight
• (likely) Watch crashing during the night or in the morning, losing the last monitoring data file in the crash. Connect the watch to a computer, and have a look at the folder //GARMIN/Debug. If there is a fileerr_log.txt (or .bak), open it with a text editor (such as Notepad), and see whether the time of the last crashlog corresponds to the end time of the missing window. If so, report it to Garmin, and send them the file too.
• (possible) reboot due to a memory leakage either in the firmware or in one of Connect IQ apps or watchfaces. If you use any CIQ apps/watchfaces, try uninstalling them and see whether it helps. Performing a soft-reset (pressing the Light button for some 30s) before going to sleep would prevent a memory-leakage-induced reboot for a few hours or days. (this is similar to the previous case, so there should be a record of it in the fileerr_log)
• (possible) conflict with the automatic nightly Altimeter Calibration. It is possible that the data file gets corrupted due to some conflict during the nightly altimeter calibration, when the watch communicates intensively with the phone. In the morning, check the altimeter or barometer graph, and see whether there is an abrupt change at the time corresponding to the end of the missing period.
• (possible, though not very likely) Insufficient or damaged storage. Check out how much free storage there is on the watch. Delete old Activities, and other unneeded files (old courses, workouts, all languages, etc), and see whether it helps.
• (possible) conflict with the update routine. The watch regularly downloads diverse updates - main firmware, Sensor Hub updates, GPS firmware update, Time Zones, language files, and some others. Often the watch restarts after such update, and data that is not synced may get lost. If your watch repeatedly and unsuccessfully tries to update one of its components, it could result in the HR data loss. Check out for updates with Garmin Express with the watch connected over the USB cable to a computer - it should install all pending updates.
• (possible) - Sync problems. Perhaps the data gets lost during a failed sync attempt. Normally it should not happen, but it cannot be excluded. If you are using an Android phone, check out the Device Sync Audits accessible at the bottom of the Settings menu of Garmin Connect.

I certainly forgot some other possibilities, but basically, for eliminating some of the possible reasons, I recommend the following:

1. Clean up the storage: remove all files from //GARMIN/Activity, //GARMIN/RemoteSW, //GARMIN/Text (keep just the language file you use), unneeded files from //GARMIN/Courses and //GARMIN/Workouts
2. Assure yourself that Battery Saver is not enabled during sleep
3. Uninstall all Connect IQ apps / watchfaces
4. Soft-reset or reboot the watch before sleep
5. Disable Bluetooth ('Phone' in the Controls menu) before going to sleep
6. Check the file //GARMIN/Debug/filerr_log
7. Check the Device Sync Audit

It may help narrowing down the culprit. Still, requesting a replacement from Garmin, may be the easiest way out. I would contact them again, and insist. 

Thanks for this long and very useful reply. You have put in a lot more effort that Garmin support did. It will take me some time to run through your suggestions. My suspicion is that it is this: "the data gets lost during a failed sync attempt".

This morning I woke at 8:00, opened the Android Connect app shortly after and watched a sync that finished much faster than it usually would. I then had all data missing from 4:00-8:00. I have sent the Device Sync Audits to Garmin support. I will post all of the info in another reply in this thread. 

8697643 said:

My suspicion is that it is this: "the data gets lost during a failed sync attempt".

To confirm or exclude this option, you could disable Bluetooth on the watch (option 'Phone' in the Controls menu) before going to sleep, and in the morning syncing over the USB cable to a computer with Garmin Express instead.

I will give that a try.

Looking at the device sync audits, the one that occurred when the data blackout began (Fri, Dec 15 2023 @ 3:46 AM) has very long 'posted' times compared to usual. I am guessing that this is the duration of the request when data is being posted to Garmin Connect. I wonder if there is a timeout happening that is causing a failure for the next sync.

---Sync Info---
******************** SYNC RESULT ********************
Upload Status=SUCCESSFUL
Download Status=SUCCESSFUL (No item to process)
Time Sync Status=SUCCESSFUL
Overall Sync Status=SUCCESSFUL
Origin=5037_SYNC_REQUEST_MESSAGE__VISIBLE_IF_FILES
*****************************************************
UPLOAD:
LISTED (Supported=[4, 32, 35, 38, 44, 41, 49, -11, -12, -9]; Uploadable=[FIT_TYPE_71, FIT_TYPE_70, FIT_TYPE_73, FIT_TYPE_72, GPSData, FIT_TYPE_52, FIT_TYPE_74, KPI, FIT_TYPE_32, FIT_TYPE_35, FIT_TYPE_57, FIT_TYPE_58, FIT_TYPE_38, FIT_TYPE_9, FitnessHistory, IQErrorReports, GOLF_SCORECARD, BACKUP_SUPPLEMENTARY, FIT_TYPE_61, ErrorShutdownReports, FIT_TYPE_41, FIT_TYPE_44, FIT_TYPE_66, FIT_TYPE_68, BACKUP_PRIMARY, FIT_TYPE_28, FIT_TYPE_49, FIT_TYPE_4, BLELogs, ULFLogs, WELLNESS_TYPE_1]) { listed=996ms }
- 1 (80/SEGMENT_LIST/367B): ARCHIVED { extracted=234ms posted=343ms archived=168ms }
- 233 (80/MONITORING_B/1826B): ARCHIVED { extracted=824ms posted=346ms archived=179ms }
- 222 (80/MONITORING_B/7969B): ARCHIVED { extracted=1569ms posted=2000ms archived=49ms }
- 118 (80/BIOMETRIC_DATA/333B): ARCHIVED { extracted=86ms posted=14553ms archived=91ms }
- 111 (80/BIOMETRIC_DATA/666B): ARCHIVED { extracted=368ms posted=25242ms archived=217ms }

The next sync at Fri, Dec 15 2023 @ 8:04 AM:

---Sync Info---
******************** SYNC RESULT ********************
Upload Status=SUCCESSFUL
Download Status=SUCCESSFUL (No item to process)
Time Sync Status=SUCCESSFUL
Overall Sync Status=SUCCESSFUL
Origin=5037_SYNC_REQUEST_MESSAGE__VISIBLE_IF_FILES
*****************************************************
UPLOAD:
LISTED (Supported=[4, 32, 35, 38, 44, 41, 49, -11, -12, -9]; Uploadable=[FIT_TYPE_71, FIT_TYPE_70, FIT_TYPE_73, FIT_TYPE_72, GPSData, FIT_TYPE_52, FIT_TYPE_74, KPI, FIT_TYPE_32, FIT_TYPE_35, FIT_TYPE_57, FIT_TYPE_58, FIT_TYPE_38, FIT_TYPE_9, FitnessHistory, IQErrorReports, GOLF_SCORECARD, BACKUP_SUPPLEMENTARY, FIT_TYPE_61, ErrorShutdownReports, FIT_TYPE_41, FIT_TYPE_44, FIT_TYPE_66, FIT_TYPE_68, BACKUP_PRIMARY, FIT_TYPE_28, FIT_TYPE_49, FIT_TYPE_4, BLELogs, ULFLogs, WELLNESS_TYPE_1]) { listed=1000ms }
- 1 (80/SEGMENT_LIST/367B): ARCHIVED { extracted=998ms posted=356ms archived=344ms }
- 222 (80/MONITORING_B/466B): ARCHIVED { extracted=564ms posted=200ms archived=494ms }
- 119 (80/BIOMETRIC_DATA/341B): ARCHIVED { extracted=568ms posted=1425ms archived=170ms }
- 233 (80/SLEEP_DATA/789B): ARCHIVED { extracted=720ms posted=1518ms archived=184ms }

Yes, 25s for posting the data to the server is rather long, telling that there were probably some connectivity problems, but there is nothing in the audit signaling a failure.

As I wrote, I recommend disabling the BT syncing (minimally during the night till the morning), and syncing exclusively over the cable for a few days, to see whether it makes any difference.