To cut down on the data being sent through Firefox Sync, there are some limitations when it comes to syncing history. Firefox Sync can only sync up to 5000 history items and it will not sync history items that are older than <strike>60 days</strike> 30 days.

CORRECTION ABOVE: Firefox will not send history items to Firefox Sync if they are older than 30 days. Similarly, Firefox will not receive items from the Firefox Sync system if they are older than 60 days. For example, if a history item is sent and stored on Firefox Sync and you add a new device to Firefox Sync after the 60 days, that item will not be sent to the new device, even if it is in the Firefox Sync storage.

Given that you have more than 10,000 items to sync, which you have said are "old", it's entirely possible that not all of the items will sync.

If you do happen to need all of the previous history items on another computer, your best bet is to make a local backup of your Firefox Profile folder and transfer it to the other computer.

Hope this helps.

Wesley Branton said

To cut down on the data being sent through Firefox Sync, there are some limitations when it comes to syncing history. Firefox Sync can only sync up to 5000 history items and it will not sync history items that are older than 60 days. Given that you have more than 10,000 items to sync, which you have said are "old", it's entirely possible that not all of the items will sync. If you do happen to need all of the previous history items on another computer, your best bet is to make a local backup of your Firefox Profile folder and transfer it to the other computer. Hope this helps.

Thank you for the reply. Has this limit been scrapped / removed from support.mozilla.org's main Q&A system?

At the moment, only Firefox For Android says bookmarks cannot exceed 5000 bookmarks. Source here.

If you have more than 5,000 bookmarks in your Firefox profile, Firefox for Android won't sync them. Some limitations in Android and Sync itself make larger quantities of bookmarks unreliable, so this limit is there to protect your data.

This 2011 Mozilla post claims there is a 25 MB Sync limit & 60 days in comment 100, but also states we should be seeing warnings in the Sync UI. No warnings have appeared.

If this is true, I'm sad to hear it. There was no warning in the Sync UI, there is negligible to zero documentation, and I've already built up a history on both systems from over 60 days, so the profile copy is not possible. And, as far as I can see, there's no clean way to merge two history files from two Firefox installs.

I would've gladly paid for the extra storage space & bandwidth costs, but that request link is already 404 (it is from 2011, after all).

Thank you for confirming the nail in the coffin here. Much appreciated, Wesley.

I'm not sure that the limit has ever been included in any of the Mozilla documentation on this website. I don't think it has, but I may be wrong.

Also, I've made a correction to my above post. It appears that the 60 day limit is for data being sent from Firefox Sync to a browser. The limit for data being sent from a browser to Firefox Sync is actually 30 days.

So, Firefox Sync can keep history data for up to 60 days on the servers, but browsers can only send it the most recent 30 days of history.

My answer is based off of a bug report (see bug 985930) filed in 2014. Although the bug is a bit on the older side, I don't see any indication that the system has changed since that time.

You can copy places.sqlite from the old device to the new device with Firefox closed. Best is to avoid copying a full profile folder as this can (will) cause issues.

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Folder/Directory:
  Windows: Open Folder; Linux: Open Directory; Mac: Show in Finder
• https://support.mozilla.org/en-US/kb/Profiles

See also:

• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

Wesley Branton said

I'm not sure that the limit has ever been included in any of the Mozilla documentation on this website. I don't think it has, but I may be wrong. Also, I've made a correction to my above post. It appears that the 60 day limit is for data being sent from Firefox Sync to a browser. The limit for data being sent from a browser to Firefox Sync is actually 30 days. So, Firefox Sync can keep history data for up to 60 days on the servers, but browsers can only send it the most recent 30 days of history. My answer is based off of a bug report (see bug 985930) filed in 2014. Although the bug is a bit on the older side, I don't see any indication that the system has changed since that time.

Thank you so much for checking this; I'm sorry to see it. However, you're right.

I only wish this was present in the UI somewhere. Hopefully, this can be added in a future update as it seems like key information.

cor-el said

You can copy places.sqlite from the old device to the new device with Firefox closed. Best is to avoid copying a full profile folder as this can (will) cause issues. You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Folder/Directory:
  Windows: Open Folder; Linux: Open Directory; Mac: Show in Finder
• https://support.mozilla.org/en-US/kb/Profiles

See also:

• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

Thank you for the update, cor-el. Unfortunately, as mentioned above, I will lose the now ~1,000 new history items on the 2nd system. Merging two places.sqlite files is involved, if not also poorly documented.

I may need to move on and find a different system, if not browser, all together. For those reading this post later, I might look at History Search, which (for a monthly subscription) will sync your browser history to a separate, seemingly high-quality indexed private cloud database.

If there are any Mozilla employees out there, I'd love to pay more to cover the storage & bandwidth for a 50k history item list. My use case is probably unusual: I do a significant amount of research (easily 200+ URLs a day) and my memory is just good enough to remember certain details from months and months ago, but not enough for a web search.

Thank you both for your replies. Onward.

You can use this Nirsoft utility to export the history or do a copy and paste form history to bookmarks in the Bookmarks Manager (Library) to have the history included in a bookmarks HTML backup. Only if you use places.sqlite you will be able to fully restore the history and this works instantly.

• http://www.nirsoft.net/utils/browsing_history_view.html