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Help Mozilla Services Operations debug what’s wrong with Sync

This post is for historical purposes only. Please do not send us any more log data at this time. Thank you!


TL;DR: Paste your most recent about:sync-log into a and send a link to @mozservices for us to check out.

Sometimes when there’s a problem with Firefox Sync, Mozilla Services Operations (@mozservices) needs some info to figure out the root cause

We strive to make sure Sync is an always-available service, but as with any complex infrastructure that is both growing rapidly & and being actively developed, we encounter the occasional glitch, outage, or obscure performance problem that we have trouble solving through what we can reproduce in our testing environments.

That’s where you, as a user of Sync, can help us out with very little effort.

Let’s get to it

  1. Get the Sync log from the browser having problems
    • Firefox 7+
      1. Enter “about:sync-log” in your Firefox address bar.
      2. Find the last error report file in the list and click on it. It should be called something like error-1317675754221.txt
        • If the log file list is empty or only contains outdated logs (you can tell by the dates), go to about:config, find the services.sync.log.appender.file.logOnSuccess preference, set it to true, and sync again. Then repeat these steps.
        • If you have a Sync problem, but there are no error reports but there are logs (named something like 1317425079289.log) or success reports (named something like success-1317547966983.txt), click on the most recent log file.
    • Firefox 6 or older
      First…you should *really* upgrade your Firefox. Why are you running this old version? But if you insist…

      1. Enter “about:config” in your Firefox address bar.
      2. Find the services.sync.log.appender.debugLog.enabled preference and set it to true
      3. Restart the browser. The preference change will not take effect otherwise!
      4. Sync again to reproduce the problem.
      5. Enter “about:sync-log” in your Firefox address bar
  2. Copy the contents into your clipboard
    • Mac: Command-A Command-C
    • Linux/Windows: Ctrl-A Ctrl-C
  3. Paste the logs into a pastebin
    1. Go to (or your alternate pastebin provider of choice)
    2. Paste (Command-V or Ctrl-V) your clipboard into the text box
    3. Change the retention to “a month”
    4. Click “Send”
    5. Copy the resulting URL from your address bar into your clipboard
  4. Link us to your pastebin
    • Pick your media:
      1. Twitter: @mozservices
        DM or just public msg to us — your call.
      2. IRC: #sync on
    • Paste the URL from pastebin with a brief description of what you’re experiencing
  5. Done. If we have follow-up questions or suggestions, we’ll contact you (hopefully shortly). Of course, if your problem goes away (either through direct action or inaction), please let us know.


Thanks for your help. There have been instances where a user’s logs provided exactly the information we needed to fix a problem that affected many other Sync users that, for whatever reason, we couldn’t duplicate or were missed by our testing.




  1. denis

    That’s normally to have some errors once in hundred years, anyway i’m with you, keep your services as always in a good condition, that’n not skype, i love you anyway, always!!! the problems are not the problems, when it is opensorce, and mozilla, isn’t it? sorry for my poor eng :)

    Posted on 03-Oct-11 at 17:06 | Permalink
  2. Lisa Rowley

    Where does one find the sync log if you are running the mac version of Firefox? My sync hasn’t worked for a few days…

    Posted on 03-Oct-11 at 18:41 | Permalink
  3. jv

    Lisa Rowley – In about:sync-log.

    Posted on 04-Oct-11 at 09:41 | Permalink
  4. Here’s a tip: Add a button in the Sync config to upload the latest error report straight to you guys. That would make it a bit easier. :)

    Posted on 03-Oct-11 at 23:43 | Permalink
  5. jv

    Natanael L – We have such a feature in development. Believe me, we (Ops) want that at least as much as you do!

    Posted on 04-Oct-11 at 09:38 | Permalink
  6. I use FF 7+ and would like to help with the Synch issue. I cannot figure out how to follow this instruction: Go to about:sync-log in Firefox.

    When I go to the “about” tab in FF I don’t see anything like a synch log option. Please advise.

    Posted on 04-Oct-11 at 06:40 | Permalink
  7. jv

    Steve – I will update the wording in the write-up, but you should be typing “about:sync-log” in your address bar.

    Posted on 04-Oct-11 at 09:37 | Permalink
  8. <3 for mozilla

    Posted on 04-Oct-11 at 06:58 | Permalink
  9. imd

    IRC is blocked at my uni and I don’t use twitter—do you do email?

    Posted on 04-Oct-11 at 08:47 | Permalink
  10. jv

    imd – Sorry, we chose not to have an ops-wide “support” email channel. You can always get creative and tunnel out somewhere to run irssi in an ssh session. They don’t block that, right?

    Posted on 04-Oct-11 at 09:59 | Permalink
  11. Trenton

    I am unable to Purge or Delete my Sync account. Is this a current problem for anyone else?

    Posted on 10-Oct-11 at 21:15 | Permalink
  12. jv

    Trenton — we would need to know what error you’re seeing to help diagnose.

    Posted on 11-Oct-11 at 09:57 | Permalink
  13. STeve

    I have sumbitted fault on mozservices but dont have an email address to report it to….. Any clues ??

    Posted on 11-Oct-11 at 16:01 | Permalink
  14. jv

    STeve — conversing via twitter is preferred so that the conversation might help others in the community. When was your message? I don’t see anything from the last few days that we didn’t respond to directly…

    Posted on 11-Oct-11 at 16:10 | Permalink
  15. STeve

    thx for the fast reply. I don’t have a twitter account and am a little unsure if posting the data publicly is a good idea.
    Actually all I need is to get my sync working again. I had loads of tabs setup and they disappeared today.
    I continually get the error “sync encountered an error while connecting server incorrectly configured”

    Posted on 11-Oct-11 at 16:20 | Permalink
  16. jv

    STeve — you’re welcome to jump on the #sync channel on irc:// (you can connect encrypted, if you wish) where you can post a pastebin link. However, there’s really nothing exciting in your sync logs…

    Posted on 11-Oct-11 at 16:28 | Permalink
  17. mindman

    I’m trying to post the url from pastebin on “IRC: #sync on”, but it doesn’t exist!! Getting frustrated with Sync not working…

    Posted on 11-Oct-11 at 18:15 | Permalink
  18. jv

    mindman — what IRC client are you using?

    Posted on 12-Oct-11 at 10:37 | Permalink
  19. STeve

    OK I am quite annoyed now. I have trawled through loads of support docs and cannot recover the tabs that were synced but have now disappeared. This is not the first time this has happened.
    Does anyone from firefox have a solution ??

    Posted on 12-Oct-11 at 15:10 | Permalink
  20. mindman

    jv – I am using Chatzilla

    Posted on 13-Oct-11 at 02:32 | Permalink
  21. Bruce Schadel

    Did the pastebin again but twitter is not working tonight. Still get “Incorrect account name or password” error even though changes made on my other PC propagate to this one. Have tried everything short of buying a new PC.

    Posted on 01-Mar-12 at 18:48 | Permalink