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Sync log error

  • since the very first day, my sync log in email has a message that there was an error with deleting one or more records on the server.  It comes on every entry.  What does this mean ?
  • Is it possible to provide us with a copy/paste of those error sync-messages log?

  • Here is a recent log.  Please not the sync of some deletions failed.  That appears in every log from the very first day.

    13:56:08 Synchronizer Version 14.0.6102

    13:56:08 Synchronizing Mailbox 'Tim Stone'

    13:56:08 Synchronizing local changes in folder 'Drafts'

    13:56:08 Uploading to server ''

    13:56:08 Synchronization of some deletions failed.

    13:56:08 [0-130]

    13:56:08   1 item(s) deleted in online folder

    13:56:08 Done

  • Hello TimStone,

    Would you please check whether any important items which exist in 'Draft'  can't be deleted in Outlook client?
    Besides, try to manually delete Outlook Data File (.ost file) with the following steps to see if it works.
    1. Open Outlook, click File->Account settings.
    2. Lookup and remember the location of your account's.ost file.
    In generally, it will be locate in: C:\Users\user\AppData\Local\Microsoft\Outlook\user account.
    3. Close Outlook client.
    4. Delete this .ost file.

    Grace Shi

  • I have exactly the same problem.   It appears to be a common issue with many people every time anything is deleted from a folder.   This includes sending an email because it means deleting the copy on Drafts.


    Deleting and rebuilding the .ost file is not practical because of size.


    The messages always seem to be deleted both on the server and in Outlook but it's annoying to have these message pop up all the time.

  • Hello Mike4QL,

    Sync between Outlook and server is done automatically. If a sync error happened, it will be recorded in a sync issue log.  Sync issue happened may due to network or local environment. However, if syncing something is failed at this time, it will be synced again in the next time. Besides, it will not affect us experience Outlook.
    Do the sync errors in your side include some operation failed? For example,  can't delete items, or can't send/receive emails.

    Grace Shi

  • Hi Grace,

    I am migrating from a LAN based Exchange Server (SBS 2008) to Office365.  Since the client end previously worked flawlessly I think we can rule out any local configuration problems.

    I cannect to the Interent through 2 ADSL lines, both running close to or at their maximum sync speed, using a dual WAN laod balancing router which is very lightly loaded.  So I think we can rule network issues, at the local end anyway.

    Since I'm only transferring a single mailbox at the moment I couldn't using the migration tools so a transferred the mailbox by having an account for each server and copying the messages between them.  While doing this I sometimes had to empty a folder with several thousand messages and the Sync Error messages appeared whenever I did.

    I now have all mailbox content transferred and I've closed down the old account and work solely with Office365.

    Since posting the message this morning I have been watching it more closely and I think I know why this occurs.  

    I have some RSS Feeds and messages are added to these locally.  It is my habit to delete RSS messages once I've read them and this causes a Sync Error and I think I may be doing this before it has been synced with the server.  Since the error means it couldn't sync a local delete because the message doesn't exist on the server this makes perfect sense.  I suppose syncing to Office365 is less frequent than it was with a local server and that's why I haven't seen it before.

    It is still a bug, though, since it should recognise that the deleted message hasn't yet been synced or it should apply the syncs in order so the message is created and then deleted.

    Sorry this is a bit long winded.  I hope it makes sense.


  • Hello Mike,

    Thanks for your sharing.
    Sync errors are recorded in error logs, successful sync will not be recorded. So when syncing something is failed at this time, it will be fixed at the next sync while it will not recorded.
    If haven't experience those situations: for examples, can't delete files or can't remove emails/folders, you may feel free about sync error. It will not affect us using Outlook client.

    Grace Shi

  • Rebuilding the OST file has no effect ....the problem s still there.  I just migrated from Sherweb Hosted Exchange 2007 and very rarely had these errors.  Now thse errors are constant.  I will continue to research this but it needs to e resolved and seems to be related to the 365 server and not the client.  The connection is fast and the issue is not machine dependant.  

    I hope someone has a resolution.


  • Just a note, might want to take a look at

    Apparently they are still researching it

    There is another thread started some 18 months ago at discussing the same thing, they also purport that it still exists in Exchange 2010 SP2\


  • I've done this [delete .ost file as suggested above] but I'm still getting the sync error messages. Every time I send a message from Outlook I get a Sync error. I also get them when I delete messages from the Junk mail folder. Looking at the forums and other tech support listings a lot of people seem to be experiencing this problem. The consensus seems to be that it is something to do with the Outlook 2010 client. There are quite a few suggestions about solving this problem but none of them seem to work. Does anyone know if MS recognize this as a bug to be fixed? It seems to be common for people using O365 with Outlook cached mode. We cannot recommend implementation of 0365 plans until this problem is fixed.

  • Hi Martini,

    Thanks for your posting here.
    In general, the sync error may be caused if the item that is being deleted no longer exists on your Exchange mailbox or has already been deleted from the mailbox. In this situation, would you please check whether any important items which exist in 'Draft' can be deleted in your local client Outlook configured Online mode? If you can delete it, please feel free about the sync error.

    Sync Issues folder for Outlook 2010 contains warnings such as "Synchronization of some deletions failed"

    If this doesn’t help you, it recommends create a new thread about your detailed situation for better help.

    Grace Shi

  • Yes. The situation is as described in . It appears that a lot of people are experiencing this problem. We are getting sync error messages every time we send a message from outlook via o365. We're holding off implementation of 0365 until we get this problem sorted out. Do you have any visibility when a solution to this problem will become available? Looking at the various forums it appears to have been outstanding for over 18months now. Hopefully it won't take another 18 months?

  • Martini,

    This has been an ongoing issue that Microsoft has shown no interest in doing anything about. Like many others, you will get the boiler plate answers here that have been around forever.   I made the mistake of thinking this would get resolved and I will not recomend this service to my clients.  With the type of support I have seen demostrated by this forum (in place of an actual 800 number that someone answers who is knowlageable and speaks english clearly and unstandably) this is not a service you would want to recomend to anyone who's business depends on it.  I am surprised people arent leaving in huge numbers to go to the more reputable service providers out there who respond quickly and profesionally with "REAL ANSWERS".  Good Luck!!

  • Hi,

    Thanks for the feedback. This looks like a tricky problem. I've done a bit more research using different client workstations and Outlook Web Access (owa). There's been a fair bit written about this problem including a couple of long threads going back  about 18 months. I'll post some links in a follow up message. Just to say here that I've managed to make a bit of progress dealing with my specific problems. First off, I discovered that I've been dealing with two distinct 'sync error' problems ...

    1. The first relates to 'sync errors' generated during the process of deleting messages, and emptying the deleted message folder in Outlook.

    2. The second problem relates to 'sync error' messages that are generated following the sending of a message from Outlook via O365/Exchange.

    I've managed to reproduce the 'sync errors' reliably for both problem conditions on different workstations - and to get a fix.

    Problem 1) above occurs when you delete messages from the Inbox and then immediately use the 'Empty Folder' option to remove the deleted messages from the Deleted Messages Folder. What appears to happen is that during the subsequent sync cycle that Outlook discovers that the messages it's trying to delete from the client .ost file are already missing so generates an error message. FIX for this is to leave messages in the Deleted Message folder for a couple of minutes [so they sync through server side] before emptying the folder. The empty delted message folder then works without generating a sync error. Not sure how a  'proper' fix for this could be engineered as it probably involves a change to the synchronizer sofware itself. However at least, pending any 'proper' MS fix, it explains how these error message are generated and how they can be avoided.

    Problem 2) - in our situation - occurs due to the use of an 'anti-virus' Outlook add-in. We use Kaspersky Security Software and this installs an anti-virus plug-in to Outlook. With this plug-in disabled then messages can be sent from Outlook [via O365] without generating 'sync errors'. To check whether you have (need to disable) this plug in Outlook Go: File:Options:Add-Ins and check the list of Add-Ins and if necessary disable. My assumption is that this Kaspersky anti-virus COM Add-In causes some delay in the processing of email transfers that disrupts the performance of the Outlook Sync component. Presumably other similar email anti-virus add-ins may give rise to a similar problem. I guess if you're having these sync errors it's worth checking what add-ins are installed/enabled.

    I have experienced a few 'proper' sync errors while testing but these have been due to genuine connection problems and the sync error messages have always correctly saved/pointed to the problem allowing for the recovery of data without loss. Since fixing 1) and 2) above I'm not experiencing 'sync errors'.

    Overall the Outlook 'sync' cycle does seem sensitive to problems. Looking back this is not an exclusive O365 problem - there is a lot of discussion about similar problems with Exchange/Outlook 2010 going back to 2010. There are a number of registry settings that affect the detailed performance of the Outlook synchronizer and it may be necessary to explore these for some network connections.

    I'll post any further notes on these problems as I gain further experience.