Dropbox app won't start on M1 Mac running Big Sur

[MikeLV]

I just got a new MacBook Air M1 running BigSur.  Dropbox does show up in the Finder sidebar and it appears the Dropbox files and folders on my Mac have synced with Dropbox.com.  However the dropbox icon does not show up in the tool bar at the top of the screen.  Plus, I downloaded the Dropbox app but it won't start.  error message is shown below.  I am not on a network share.  Don't know what is the deal with permissions.  Suggestions?

[Tim T.]

Same result. After install and login, when I hit the Next button (to open the app), I get the same error. I have never moved my Dropbox folder. I ran the app fine for months after migrating to my new Mac. This error just started a few weeks ago. Should I have disabled the admin privileges of the user before running the installer? I had them on to run the suggested Terminal commands. I left admin privileges on when installing. I am at a loss, and this is causing major headaches for two work projects. I have to download files from the web version of Dropbox, modify them and them upload them back. There's lots of room for problems. My local Dropbox no longer reflects the online version (not sync'd, because I cannot get Dropbox app to start. Here's the full log:

bn.BUILD_KEY: Dropbox

bn.VERSION: 127.4.4265

bn.constants.WINDOWS_SHELL_EXT_VERSION: 48

bn.is_frozen: True

machine_id: 70cb2f9b-0398-5ffb-bcd1-06f602617645

pid: 8824

ppid: 1

uid: 502

user_info: pwd.struct_passwd(pw_name='tntozer', pw_passwd='********', pw_uid=502, pw_gid=20, pw_gecos='T N Tozer', pw_dir='/Users/tntozer', pw_shell='/bin/bash')

effective_user_info: pwd.struct_passwd(pw_name='tntozer', pw_passwd='********', pw_uid=502, pw_gid=20, pw_gecos='T N Tozer', pw_dir='/Users/tntozer', pw_shell='/bin/bash')

euid: 502

gid: 20

egid: 20

group_info: grp.struct_group(gr_name='staff', gr_passwd='*', gr_gid=20, gr_mem=['root', 'tntozer', '_nsurlstoraged'])

effective_group_info: grp.struct_group(gr_name='staff', gr_passwd='*', gr_gid=20, gr_mem=['root', 'tntozer', '_nsurlstoraged'])

DYLD_LIBRARY_PATH: None

cwd: '/'

     real_path='/'

            mode=0o40755 uid=0 gid=0

     parent mode=0o40755 uid=0 gid=0

HOME: '/Users/tntozer'

appdata: '/Users/tntozer/.dropbox/instance1'

         real_path='/Users/tntozer/.dropbox/instance1'

                mode=0o40700 uid=502 gid=20

         parent mode=0o40755 uid=502 gid=20

dropbox_path: '/Users/tntozer/Dropbox'

              real_path='/Users/tntozer/Dropbox'

                    mode=0o40700 uid=502 gid=20

              parent mode=0o40755 uid=502 gid=20

sys_executable: '/Applications/Dropbox.app/Contents/MacOS/Dropbox'

                real_path='/Applications/Dropbox.app/Contents/MacOS/Dropbox'

                      mode=0o100755 uid=502 gid=20

                parent mode=0o40755 uid=502 gid=20

trace.__file__: '/Applications/Dropbox.app/Contents/Resources/python-packages.zip/dropbox/client/ui/common/boot_error.pyc'

                real_path='/Applications/Dropbox.app/Contents/Resources/python-packages.zip/dropbox/client/ui/common/boot_error.pyc'

                      not found

                parent not found

tempdir: '/var/folders/nb/wl1n6xsd5f9__bw4ldx8gl9w0000gp/T'

         real_path='/private/var/folders/nb/wl1n6xsd5f9__bw4ldx8gl9w0000gp/T'

                mode=0o40700 uid=502 gid=20

         parent mode=0o40755 uid=502 gid=20

Traceback (most recent call last):

  File "dropbox/client/main.pyc", line 827, in wrapper

  File "dropbox/client/main.pyc", line 6650, in finish_dropbox_boot

  File "dropbox/client/message_queue.pyc", line 307, in _wrapped

  File "dropbox/client/main.pyc", line 6147, in _init_components_for_account

  File "dropbox/client/main.pyc", line 6073, in create_sync_engine

  File "dropbox/sync_engine_boundary/factory.pyc", line 225, in make_sync_engine

  File "dropbox/sync_engine/nucleus/classic_client/sync_engine.pyc", line 278, in __init__

  File "dropbox/sync_engine/nucleus/classic_client/modern_client/modern_client.pyc", line 219, in __init__

  File "dropbox/sync_engine/nucleus/classic_client/modern_client/base.pyc", line 150, in __init__

  File "dropbox/sync_engine/nucleus/classic_client/thin_adapter/in_proc.pyc", line 223, in __init__

  File "dropbox/sync_engine/nucleus/classic_client/thin_adapter/in_proc.pyc", line 591, in _init_new_engine_locked

  File "dropbox/sync_engine/nucleus/thin_client/client.pyc", line 182, in __init__

  File "desktop/extensions/nucleus/nucleus_python.pyx", line 76, in nucleus_python.NucleusSyncEngine.__cinit__

nucleus_python.SyncEngineError: "Initializing engine |>> Initializing filesystem |>> Marking Nucleus cache directory as ignored |>> Writing to xattr |>> fsetxattr syscall: write_xattr |>> Permission denied"

[MikeB2]

So, it turns out my anti-ransomware (folder/file protection) software was causing issues.  It may have started to block Dropbox after an update or something(?)  I removed then restored authorization for Dropbox to access my protected folders (including the Dropbox folder), and it seems to be working again.

[Tim T.]

I tried this (removing then reauthorizing the anti-ransomware protection). It didn't work for me (at least immediately). Did you need to do the advanced install again (e.g., remove authorization, then do advanced install, then re-authorize protection)?

[MikeB2]

I ran the advanced reinstall, it didn't work.  Then I updated the protection software, and Dropbox started working immediately...

[Tim T.]

It definitely has to do with my Anti-virus software (includes ransomware protection). If I remove the Dropbox app's access in the anti-ransomware section of the software, and the Dropbox files from the list of protected folders, then do an advanced install, then Dropbox will start. If I add Dropbox access and folders back into ransomware protection, Dropbox will still run. However, if I have to quit Dropbox (or, for example, restart the Mac), when I try to restart Dropbox I get the same can't launch Dropbox error—even if I have the antivirus/anti-ransomware software turned off. Then I have to go through this whole process again. I don't know a working solution. I'll contact the antivirus software developer and see if they changed something a few weeks ago.

[Tim T.]

I've tried several tests (one thing was to turn off full disk access for Dropbox in the macOS System Preferences). 

The reality is that, if I have anti-ransomware protection authorizing Dropbox access and protection of the Dropbox folder, Dropbox cannot start if opened. If those protections are turned off and the antivirus software is quit, Dropbox will open. Once Dropbox has started, the antivirus software can be opened and anti-ransomware protections configured for Dropbox. They have to be deleted and the software quit before re-starting Dropbox.

A fudgy-work-a-round, but it works for now.