Activity storage almost full?

I think the activities are still stored on the watch and if you have a lot of music / apps and maps installed the storage can get quite full.

What you can try is to reset the activity cache by going to settings - > System - > Reset - > delete activities. This will delete all stored activities from your watch. Those synchronized on GC will remain on GC.

You can also connect your watch to the Garmin Express PC App. There you can view the storage usage of your fenix. This would be quite interesting... 

I've got this message twice already. There was no data lost, everything was uploaded to GC. Still could not understand what happened. I still have about 16 GB free, so unless the activities has some limit, there should definetely not be a storage problem. For the 1st time I could not really figure out the details. But the 2nd time it happened, I had two running activities one after each other. They were small activities (tests for running under 1km) and about 1min or less apart. I had the phone with me, but it could be it didn't sync after the 1st test (didn't check). I've got the message after the 2nd run/test. What's even more interesting, one day before I've deleted some of the activities from the watch, so I should have had plenty of space even if the activities had some limit independ of the storage space. The watch auto deleted some recent activities (Feb - March), but kept some activities from Jan-Dec (sychronized from an Edge device), and I found that annoying. So I did a cleanup, deleted on the watch all the old activities and still I got this message about storage almost full. I have no music, only Europe maps and as already mentioned about 16 GB free. 

Report it to Garmin Support. Older files should be automatically deleted as the storage fills. This might imply it’s not the case. 

I did check Garmin express and it’s plenty of storage left. And one month of activity’s should not fill the watch and I think I heard that if it’s getting full it will delete the oldest ones?

I don’t want to erase or factory reset every time something is weird and that is often what support tells you.

I can’t erase every thing every time something’ happens, I would have to spend hours setting up the watch all the time.

Seems to be a bug definitely.

If you have 16 GB free I expect you have a Saphire version with 32 GB of storage right?

Another thing that would be interesting is what the garmin connect IQ app is saying about free storage for apps etc. 

Yes Saphire with 32 GB. Garmin Connect IQ is saying 11 installed, 22 remaining. Space available 19.43 MB. 1 watch face, 7 apps and 3 data fields. The almost full storage message was displayed after Ski and after Run. None of them is using any of the downloaded data fields. Run is even in default configuration, never customized it. 

Report it as a bug to Garmin, since the watch should automatically overwrite old workouts without error messages or requirement that user deletes previously saved activities to make room for new ones. 

The same goes for me. Message: "Activity log almost full" but only done 94 activities so far. I also have the 32GB Sapphire version with no music or extra maps installed.
I never had such a message with the Fenix 6, not even after more than a year.

I sent in a report to outdoor.beta address.
But maybe it should've been another address?