Microsoft Outlook Creates Many Conflicting Contact Records

  1. Posts : 5
    Windows 10

    Microsoft Outlook Creates Many Conflicting Contact Records

    I can't seem to figure out why I keep running into conflicts with my Outlook Contact records. I only ever edit a particular Contact on 1 PC at a time. Yet, something seems to modify the contact on the Exchange server (Office 365), and when I save the contact locally, a Conflict is produced. Here is an example of what seems to be causing the error as reported in Outlook's sync issues log:

    9:31:56 Not equal (conflict) named property: 0x859C0102
    9:31:56 Local modification: {16:31:47.0473 18/03/2020 [DD/MM/YYYY]}
    9:31:56 Remote modification: {16:31:55.0552 18/03/2020 [DD/MM/YYYY]}
    9:31:56 Conflict generated, remote item is winner

    The time on my PC syncs with a national time server, so it's not like the time on my PC is off. What could be causing the "remote modification" of the Contact on the server?

    I have looked at my server settings and ensured that all add-ins are Turned Off. I'm trying to figure out what else could be modifying the Contact record on a server level so that when I save it locally, it conflicts with whatever the server did while I was editing the Contact record locally.

    I have opened Outlook in Safe Mode to ensure that no 3rd party plug-ins or extensions are causing the conflicts.

    I have tried closing Outlook on all PCs except one thinking that the other PCs with Outlook open could be causing sync errors, but that did not solve the problem.

    I have tried running Outlook in Online Mode instead of Cached Exchange Mode, but that did not solve the problem.

    I have cleared all conflicts and linked records for a particular Contact in order to edit that Contact with no "baggage" attached. Nonetheless, a conflict will still occur.

    I have cleared Offline Items from my Contacts folder to let it re-sync fresh from the Exchange server. That did not solve my problem.

    I have created a new Contacts folder in Outlook, but that did not solve the problem.

    My Outlook Conflicts folder is taking up over 10GB of space, so I'd say it's a little out of control. I only have 50GB of storage available from Office365. In case you're wondering, that's 237,779 conflicting items from years of Outlook use. :)
    Last edited by Technostud; 19 Mar 2020 at 08:36.
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  2. Caledon Ken's Avatar
    Posts : 24,207
    Windows 10 Pro x64 Version 2004


    So I assume you have a Microsoft account (Hotmail, Live,, Office 365). You said Exchange server (Office 365) so I think safe assumption.

    I did not understand your comment when you save it locally. I just edit mine in my account and they are immediately reflected on the server. Which in turn is synced with my phone

    Now I'm not running multiple copies of Outlook for the record.

    I've set my Outlook 365 / 2019 Outlook program to use the Calendar, tasks and contacts in my account as the default data folders.

    Could I ask what you are using as your default data folders. (This Computer or an Account)

    Would like to understand saving locally.

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  3. Posts : 5
    Windows 10
    Thread Starter

    Thanks for asking. I do have a Microsoft Business Account that logs into Office 365.

    When I say that I "save an Outlook Contact locally," I mean that I save the Contact on my local PC using the Outlook 2016 desktop client.

    I'm not sure if this answers your question, but my data is stored in OST files on the hard drive of each local PC.
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  4. Caledon Ken's Avatar
    Posts : 24,207
    Windows 10 Pro x64 Version 2004

    Okay let us try this.

    In Outlook click file, accounting settings, accounting setting again, Data file tab.

    Is your Office 365 set as the default for data files.

    When you click on People and the people window opens, in the upper left (navigation pane) under heading my Contacts are you storing contacts in a folder called Contacts - (This Computer Only)
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  5. Posts : 5
    Windows 10
    Thread Starter

    Is your Office 365 set as the default for data files? Yes.

    In the People navigation pane, there is no folder called "Contacts - (This Computer Only)."
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  6. Caledon Ken's Avatar
    Posts : 24,207
    Windows 10 Pro x64 Version 2004


    Went back and reread your first post.

    On second pass the size of your contact stands out. Yes you mentioned it, I didn't acknowledge.

    That is a crazy size, syncing 10GB files across devices with app starts and closing doesn't sound realistic. I have a thousand contacts, most with notes etc and I use 5MB.

    Think you should concentrate on file.

    Have you exported your contacts and then loaded them into another mail product. I would export as a csv file and then import them into a dummy gmail account. I find gmail has the best duplicate conflict resolution process.

    My thinking is loading into gmail you will get some sense as what is going on with file.
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  7. Posts : 5
    Windows 10
    Thread Starter

    I agree that the size of my Conflicts folder is huge. Remember, that's my Conflicts folder, not my Contacts folder. The reason for my post is to get to the root cause of why so many Contact records are conflicting in the first place. What could be causing the conflicts?
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  8. Caledon Ken's Avatar
    Posts : 24,207
    Windows 10 Pro x64 Version 2004

    Can't say. Maybe it is a vicious loop.

    The file is corrupt and it is huge. Every time you log on or add / edit it tries to sync again and with the size it fails to complete or adds to corruption.

    I would be looking at a way to get a clean file. I had suggested gmail contacts.
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