0x8131170A The Sync Key sent by the client is invalid. | MDaemon Technologies, Ltd.

0x8131170A The Sync Key sent by the client is invalid.


  • Since the last update, we have been experiencing issues with ActiveSync clients. The problem is that there are invalid synchronization keys, causing the clients to re-sync all mailbox emails. This is a problem because there are over 260 configured accounts, and the synchronization failures occur randomly.

    Also, it should be noted that this issue is only seen in Outlook clients. The version is Microsoft Outlook for Microsoft 365 MSO (Version 2304, Build 16.0.16327.20200) 64-bit. I'm not sure if there is any protocol incompatibility, but I don't see any more information in the logs. Is anyone else experiencing this?

     

     

     



  • Hello Javier,

    When the "The Sync Key sent by the client is invalid" error occurs, which folder ID does it reference?

    When a user experiences that error, does it occur with more than one type of folder, or does it only occur with the Inbox?

    Do the affected users have a large number of messages in their Inboxes?  If so, of those who experience this problem, how many messages does the smallest Inbox have, and how many does the largest have?


  • The problem occurs when users have too many emails in their inbox. Just yesterday, a user called me about this issue, and they had over 32,000 messages in their inbox. To prevent this from happening, I created a subfolder in their inbox and left only about 1,000 messages in it. By implementing this solution, the problem no longer occurs.


  • That's great to hear, Javier.  Let us know if you have any further questions.

    Regards,
    Jared


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