Brave Sync locks up Mac Brave browser during Mac + iPhone sync

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Description of the issue:
Syncing has locked up Brave Browser Mac
Steps to Reproduce (add as many as necessary):

  1. I made a new sync chain on my iPhone
  2. Added sync chain words to my Brave Mac browser
  3. Brave Mac and iPhone started syncing
  4. Bookmarks appear on iPhone but all disorganized - some are in my browser bar folders but many are all in the root of the bookmarks list on the iPhone
  5. Meanwhile, Brave browser on Mac is completely locked up and has been for about 30 minutes
  6. FYI - I have a ton of bookmarks. You could probably call me a bookmark hoarder. I have meticulously nested categories of bookmarks going all the way back to the late 90’s. Thousands. I don’t know how many exactly. Probably several thousand. Before Google, people like me tried to keep track of the internet, and the habit never died.

Actual Result (gifs and screenshots are welcome!):
Brave browser mac locked up during sync and not sure if it will ever recover. App is unresponsive and clicking on part of UI displays macOS RBOD

Expected result:
I would assume syncing to be a threaded behavior that runs quietly and 'nice’ly in the background

Reproduces how often:
First time trying to sync

Brave Version(about:brave): MAC
iPhone - whatever version is current release as of 2019-04-19 not sure where v# is

Reproducible on current live release (yes/no):

Additional Information:
As I noted above, I have a ton of bookmarks and nested subfolders. Best guess would be around 30,000 bookmarks, organized in dozens of top level folders with various sub folders, ie:
Media > Company1 > bookmarks
Media > Company2 > bookmarks
Current > Engineering > Electrical > bookmarks
etc above kind of organization with hundreds of folders and thousands of bookmarks

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I tried uploading an Activity Monitor process sample report but you don’t allow .txt files to be uploaded which seems kind of silly.

Here’s a link to it in case you are interested:

In Activity Monitor, all the Brave Helper processes seem to be mostly idle for my dozen or so open tabs, but the Brave Browser main process is using 110% CPU (and my Brave browser is still totally unresponsive after an hour), so it seems the sync process is running on the main thread? I imagine you need to spin the syncer off to its own thread/helper process so it can work politely in the background with big syncs.

Well, I gave up waiting and force quit Brave on my Mac. At the same time, I deleted my Mac device from the sync chain on my iPhone, thinking that upon relaunch of Brave on the Mac, it would no longer have a sync chain and stop syncing.

But now Brave just crashes a few seconds after launch. It launches, displays a default page with no content, and the ‘restore previous session’ button is displayed, and then after a few seconds Brave just crashes (whether I click the restore button or not).

What pref files in ~/Library/Application Support/BraveSoftware/Brave Browser can I trash to get Brave to launch again without crashing so I can restore my prior session and continue on with life?

I have a bunch of crash logs. Let me know how I can provide them to you. I would really appreciate some support in terms of getting Brave to launch again without completely trashing my existing set of user preferences.

In the meantime, I downloaded a Brave Nightly build and copied over the history and bookmarks and a couple other files so I have the basics of my browsing universe operational again.

I should probably write this as a separate post - but it would be great if I could easily mark as favorite or ‘star’ or checkbox tabs as default tabs that will always open when I launch Brave. I usually keep about 20-30 tabs open spread across two or three different browser windows and its sad when I lose the ‘restore session’ and didn’t remember to ‘bookmark all tabs’. I dont necessarily want to have to bookmark them to ensure they will be restored if the session is lost - rather if there was a little star or favorite icon on tabs that I could click to mark them as default tabs upon launch that would be great.

Meantime, back on the original subject - because I’m now essentially running a new install with Brave Nightly, I don’t any of my extensions, or my rewards etc. Because Brave crashes instantly! :frowning: Help!

cc @Mattches @gsarvadnya for assistance here.

Still in need of help here if any is available. Can I provide a crash log that will assist and/or can someone tell me which cache or state files I might be able to delete to get Brave running again?

@eljuno @Mattches

Well tonight the Brave nightly build I was running (because I can’t run the release version of Brave because it crashes upon launch) crashed, and when I relaunched, my ‘session’ was lost (all tabs I had open). I would really like to emphasize how important it is that Brave remember and be able to restore the prior session tabs/windows - not with a single opportunity to click the ‘restore’ button (which in this case did not appear upon relaunch), but with a menu item that remembers the last session as it was before Brave quit and can be restored at any time.

I would really appreciate some help getting the release version of Brave working again.

Also, I tried to mention all users referred to by eljuno but apparently I’m a new user and not allowed to do that.

Well, I got my current bookmarks exported from Brave Nightly, so for now, I’m going back to Chrome, which I am not happy about.

I still have my Brave-Browser folder in /Users/user/Library/Application Support/BraveSoftware/Brave-Browser so I’m hoping I’ll be able to recover my BAT and overall Brave environment. But for right now, something in the brave-browser folder crashes Brave every time it launches, and I can’t run a Nightly build given the instability I just experienced. I need to be able to restore my session - I keep too many tabs open to deal with losing it all every time!

In the meantime, there seems to be no support here, and I have not been able to find any good technical info that would help me self-troubleshoot whatever files or cache files etc are causing Brave to crash. I tried trashing /Users/user/Library/Application Support/BraveSoftware/Brave-Browser/Guest Profile/Sync Data and /Users/user/Library/Application Support/BraveSoftware/Brave-Browser-Nightly/Default/Sync Extension Settings - still crashing.

I’m sure I could trash the entire brave-browser folder but I’m trying to avoid that.

Hopefully I’ll hear from someone here soon.

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@sriram @michal


Apologies for the late reply.
I read throgh your posts and there’s a lot to unpack there. Before troubleshooting fully, I’d like to confirm a few things so that we’re on the same page:

  1. Do you have your bookmarks backed up somewhere? If not, you can export them as an HTML file and reimport them into Brave (if this step is necessary).
  2. Are you using a VPN connection when you attempt(ed) to Sync?
  3. Do you have any AV software running in the background?

I’m going to reach out to some team members, but I believe we do have a known issue with Sync when users sync a large amount of bookmarks – I will dig around for this as well.

A couple other things:
If you have you bookmarks backed up somewhere, I would recommend backing up your wallet as well and then doing a fresh install of Brave (wiping the associated profile data folder in Application support --> BraveSoftware --> Brave Browser and trashing the app). Further, an additional test may be to backup/copy the entire Brave-browser folder there, reinstall, then paste and replace the freshly installed Brave-browser folder with your saved copy.

If you replace it and Brave launches as intended, then the issue likely isn’t related to profile data. If it does crash on launch again, that’s a good indication that there’s shenanigans afoot.

Let me know what you find out – appreciate your patience and apologize again for the late response.

  1. Do you have your bookmarks backed up somewhere?

Yes - as I noted above, I managed to get my bookmarks exported back to Chrome when I gave up on Brave.

  1. Are you using a VPN connection when you attempt(ed) to Sync?


  1. Do you have any AV software running in the background?

Not at the time I was attempting to sync - just had Brave, Apple Mail, and a couple other minor apps like TextEdit and Messages open.

If you have you bookmarks backed up somewhere, I would recommend backing up your wallet as well and then doing a fresh install of Brave (wiping the associated profile data folder in Application support --> BraveSoftware --> Brave Browser and trashing the app).

I downloaded and re-installed Brave (with my existing Brave-browser folder in place).
Launched Brave - Result: crash.

I then zipped a backup copy of the Brave-Browser folder in Application Support, and trashed the Brave-browser folder. After trashing that folder, Brave launched - appearing normal like a first time install.

Further, an additional test may be to backup/copy the entire Brave-browser folder there, reinstall, then paste and replace the freshly installed Brave-browser folder with your saved copy.

Does not work. Something is corrupt in my Brave-Browser folder which crashes Brave every time.

Ok…I was troubleshooting while writing this reply, and I have determined which file is causing Brave to crash:

/Users/username/Library/Application Support/BraveSoftware/Brave-Browser/Default/Preferences

When I trash that ./Default/Preferences file from my original Brave-browser folder, then Brave will launch, and my bookmarks, wallet, etc are intact.

Examining that Preferences file in Sublime, I see now that it is filled with what appears to be many of my bookmarks, browsing history, etc.

For example:,*”:{“last_modified”:“13199750222108423”,“setting”:{“lastEngagementTime”:13199582967272164.0,“lastShortcutLaunchTime”:0.0,“pointsAddedToday”:2.1,“rawScore”:2.1}}

There are about 27500 lines in the Preferences file when I split lines on commas - so roughly 4400 of the above JSON/dictionary entries - each representing data for a different bookmark or site visited, plus hundreds of lines of other prefs for other settings, zoom settings, etc.

I can’t send you the Preferences file as it appears to contain a lot of browsing history information that is private.

Somehow, the syncing procedure I described at the beginning of this post corrupted that Preferences file and caused the crashing issue.

Why did syncing put so much data related to my bookmarks in the “Preferences” file? That seems like a bad idea. Or maybe I’m assuming incorrectly, and syncing had nothing to do with all that data being in the “Preferences” file? I’m not sure. My assumption is that syncing caused this, and the file ended up corrupt as a result.

I can tell that the file definitely contains malformed JSON, as when I set the syntax to javascript while viewing the file in Sublime, the syntax is not highlighting properly, indicating that somewhere in there is a problem, like a non-matching set of curly braces or some other issue that would cause parsing the Preferences file to fail.

I would suggest:

  1. Test syncing a huge # of bookmarks (5000 - 15000)
  2. Test Brave’s startup behavior by intentionally corrupting/malforming the JSON in the Preferences file
  3. Do not store bookmarks or sync-related data in the Preferences file
  4. Make syncing a safe threaded background process that can be started, paused, continued at next launch, etc, so there’s no issues related to locking up the GUI when there’s tons of data to sync, and less risk of data corruption if syncing is interrupted.
  5. Don’t sync using JSON - use a database to write records, so if syncing is interrupted, presumably there will be less risk of corruption (I don’t know what kind of databases are implemented in Chrome/Brave for these purposes) (edit: on second thought, I know what I wrote here sounds ignorant as no-sql databases like Mongo do write JSON files - I just meant implement the syncing in separate database records or files vs in a Preferences file which is presumably shared with other threads - I really don’t know…I should not make any assumptions about the architecture here…)
  6. Please implement a stronger feature for saving and restoring previous sessions when Brave shuts down improperly. I would really like to have a keyboard shortcut for “Save Session” that would write out all open tabs/windows to a file which could be restored at any subsequent point (ie in the History menu - History > Restore Previous Session


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