Sync between Atlas and Device Sync has been stopped - the number of unsynced documents for this app has exceeded the maximum

[Mateusz_Piwowarski]

Hey, please explain how to prevent the problem:
‘Synchronization between Atlas and Device Sync has beed stopped, due to error:
non-recoverable error processing event: the number of unsynced documents for this app has exceeded the maximum’.

What could be the cause? CPU? RAM? Too small oplog size? I’m trying in the metrics to find the causes, but haven’t found anything that stands out.

Can someone explain to me how I can speed up the synchronization of documents or increase the limit of unsynchronized documents?

[Mansoor_Omar (Manny)]

Hi Matuesz,

Thanks for posting and welcome to the community.

This error means there have been more than 100k documents in Atlas which do not comply with the device sync cloud schema that you have configured on your cloud app. For e.g. if the cloud schema requires a string field for a property but your document has objectId, this will cause a mongoencoding error which you’ll be able to see in your app logs.

To rectify this you will need to update the affected documents to bring them into compliance with the schema. The document id will be shown in your app logs under the mongoencoding error mentioned. When this limit of 100k documents is reached you will need to terminate sync and restart it after fixing the problematic documents.

Regards
Manny