"There was a sync problem." when trying to sync users

We are attempting to sync two sites but are being met with a "There was a sync problem." error after connecting and attempting to sync the first sub-site.

I have cleared options and reset everything, however the problem persists. I have two staging sites where the issue is replicated, I have debug logs enabled however nothing obvious seems to show up in the logs. Can I please have some assistance in troubleshooting? Thanks.

  • Luís

    Hi Matthew ,

    Hope you're doing well today!

    Do you have debug mode enabled on both the master site & the sub site? If so, could you try doing another sync, and share the both log files here please (indicating which log belongs to which site)?

    Note: Save the file as a .txt, because the .log extension is not allowed in the attachments.

    Also, could you follow the flowchart of the below page to determine if another plugin may be conflicting with this?


    Cheers, Luís

  • Adam Czajczyk

    Hello Matthew!

    I'm sorry for the delay on our side. We treat all the members of our community the same so please be assured that the fact you're on a trial subscription in no way affects your eligibility for a full support and the delay is a result of a slightly bigger amount of questions we received recently.

    Just for future reference - it's also better to not post more than a single post "in a row" before getting a replay from staff member. That's of course perfectly fine if you need to add something to the topic but it's also automatically marking the thread "newer" and we're supposed to answer all questions in order from "oldest" to "newest" so the waiting time would be shorter. I hope that makes sense and I apologize for keeping you waiting.

    As for the issue. I reviewed both logs and I can see that one of them suggests that operation was successful but the other one reports broken hash for requests. That is some "clue" but it still requires some more investigation.

    You mentioned that you tested it on your staging sites. Would you mind granting me a support access to both of them? You can do it using our WPMU DEV Dashboard plugin as described here:


    Since these are staging sites, may I run some tests/make changes to them in order to diagnose the issue?

    Best regards,

  • Predrag Dubajic

    Hi Matthew,

    I had a look at your sites and noticed that they are both running on outdated WP versions and the subsite is using really old version and that might just be the issue here.

    Can you try updating your subsite to at least version used on master site, or preferably update both sites to latest WP and run the sync process after that so we can check if that's indeed the issue here?

    Best regards,

  • Predrag Dubajic

    Hi Matthew,

    Could you provide us with FTP or cPanel login to both sites so we can investigate this further?

    You can send us your details using our contact form https://premium.wpmudev.org/contact/ and the template below:

    IMPORTANT: Make sure you select "I have a different question" for your topic so it doesn't go back to forums - this and the subject line ensure that it gets assigned to me.

    Subject: "Attn: Predrag Dubajic"
    - Site login url
    - WordPress admin username
    - WordPress admin password
    - FTP credentials (host/username/password)
    - cPanel credentials (host/username/password)
    - Link back to this thread for reference
    - Any other relevant urls

    Best regards,

  • Panos

    Hi Matthew ,

    Sincere apologies for the delay!

    I have made several modifications to plugin files in order to split such a large amount of users in smaller chunks.

    More detailed:

    1.It now uses ajax so you can monitor how many users have been synced. One limitation though is that you need to keep that browser tab open as it needs javascript to keep the loop going.

    2. Each time it syncs 10 users so your server doesn't time up.

    3. If you start syncing and leave page, then the next time syncing will continue from where it stopped.

    4. I have added a progress bar and a counter so you can see at which point has the syncing reached.

    5. Syncing is now starting from the newest user not from the oldest. Could be useful in some cases when you just want to sync some new users only.

    You can test these modifications at your sites, where you will see that I have already started and stopped at some point (around 830 users).

    You can download the modified plugin from your server or from here: https://www.dropbox.com/s/g1eff1upynsdaq4/user-sync.zip?dl=0 , or you can give us access so we can replace files for you :slight_smile:


  • Matthew

    Hi Panos & Predrag,

    Thanks for your help. We've been trying to test this over the last week, but we're still running into issues with the sync.

    The solution you provided with the updated sync plugin has allowed us to successfully incrementally sync (with a small number of users, with a certain user role being missed) our user database.

    However, we cannot get real-time sync (e.g. someone signs up on our master site and is synced to the slave sites straight away) on our live site.

    Real-time sync does not work on our live server - no user record is created on our sub-site, although the log reports no errors
    [2016-10-23 10:25:08][M] 02 - sending request - url=http://learn.coolaustralia.org/wp-admin/admin-ajax.php?action=user_sync_api;;***
    [2016-10-23 10:25:08][M] 03 - sending request - response=f6d2c69d2956afe7ac2a1154d63028ea;;***
    [2016-10-23 10:25:08][M] 05 - checking key true;;***
    [2016-10-23 10:25:08][M] 09 - user sync***
    [2016-10-23 10:25:08][M] 02 - sending request - url=http://learn.coolaustralia.org/wp-admin/admin-ajax.php?action=user_sync_api;;***
    [2016-10-23 10:25:08][M] 03 - sending request - response=;;***

    Interestingly real-time sync works on our test server (as setup by you guys), everything is instantaneous
    [2016-10-23 10:33:04][M] 02 - sending request - url=http://stglearn.coolaustralia.org/wp-admin/admin-ajax.php?action=user_sync_api;;***
    [2016-10-23 10:33:07][M] 03 - sending request - response=a06b30bb22109b99a834f0849843e34a;;***
    [2016-10-23 10:33:07][M] 05 - checking key true;;***
    [2016-10-23 10:33:07][M] 09 - user sync***
    [2016-10-23 10:33:07][M] 02 - sending request - url=http://stglearn.coolaustralia.org/wp-admin/admin-ajax.php?action=user_sync_api;;***
    [2016-10-23 10:33:07][M] 03 - sending request - response=;;***

    errors_s.log on the sub-site (http://learn.coolaustralia.org/) is empty as well.

    The plugin is currently working in our production environment for another site (coolaustralia.org -> enviroweek.org). We attempted to add our new site as a sub-site to the same master (coolaustralia.org -> learn.coolaustralia.org) but the user record also failed to be created on the sub-site with this scenario.

    Any idea what is going on? Any help or suggestions for what we can do/look into, we would be incredibly grateful.

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