The first diagnostic step is to run in safe mode: hold Option when you launch TB, or Help/Restart with Add-ons Disabled. Mention your antivirus program, if applicable.

Thanks, sfhowes.

The problem doesn't seem to occur when I start in safe mode. I'm using two antivirus programs: McAfee and Malwarebytes.

The only add-on that was enabled was "Lightning 6.2.4." I think it's supposed to work with TB60.4.0, which is what I'm running. Apparently, however, it doesn't.

I've disabled Lightning, so now I have no add-ons enabled (running bare TB), but not in safe mode. Will let you know if it crashes agains. Thanks again.

Note from the kb article that safe mode involves other factors besides extensions like Lightning. It's possible, but unlikely, that Lightning is the problem - unless you have large network calendars. If TB works in safe mode, launch again in safe mode, check 'Reset toolbars and controls', and click "Make changes and restart'. If that doesn't help with TB in normal mode, check that hardware acceleration is disabled when you're in normal mode (Preferences/Advanced/General). Also, check if your theme is a problem if it's not the default theme.

FWIW, I have this problem too. Virtually the same set up as the original poster - same version of TB, same version of Mac OS, same version of Lightning. I use Avast for anti-virus.

It seems that the problem started when I updated to TB 60.4.0.

I need Force Quit the app (TB) 3 or 4 times per day.

If the problem is related to antivirus (test by running OS X in safe mode), then disable the email scanning component (not the same as the real-time scan, which can be left on). As an example, for Avast:

https://help.avast.com/en/av_free/17/settings_sh_mail_basic.html

Did "Make changes and restart," to no effect. Using standard theme, and no hardware acceleration. I'll try disabling Lightning and running in normal mode for a while and will let you know how that goes.

Per the suggestion from sfhowes, I uninstalled Avast yesterday afternoon. TB hasn't frozen since I uninstalled Avast. If I get through today with no freezes, I'll assume Avast was the problem.

My internet provider (Cox) offers MacAfee security for free. Does anybody know if there are any conflicts between MacAfee and TB? If not, I will try MacAfee.

McAfee has a checkered history with TB, at least with the Windows version. No matter which program you choose, it's generally recommended to exclude the TB profile folder from AV scanning, and also to disable AV scanning of secure email connections (SSL, TLS). The real-time background scan can, and should, be left on.

http://kb.mozillazine.org/Antivirus_software

Thanks for the additional information. I read that article. The article says that Avast is one of the most compatible anti-virus apps with TB. But it appears that Avast was causing TB to freeze or hang up. Since I uninstalled Avast I have not experience a single freeze of TB. I feel safer if I have some form of anti-virus running on my Mac, but it seems like none of them play well with TB. Sigh....

Does the computer with Avast installed still freeze if you set the Mail Shield to not scan email or SSL connections? I don't use a Mac, so I can't recommend a specific AV program, but none of them should cause problems if properly configured.

I confirmed that it's not Lightning. Freezing occurs with Lightning disabled. I could restrict anti-virus scanning as suggested. That is, restrict the reach of the AV software to accommodate TB. I wonder, however, what is it about safe-mode that allows TB to work even with the AV running? Therefore, it seems possible for TB to function appropriately with AV software. Is this something that can be fixed (without running permanently in safe-mode)?

Thanks for your help! Your diagnosis of the AV software seems to have been mistaken. See below.

If TB works in safe mode, and it's not due to disabling add-ons, and resetting the toolbars and controls doesn't make any difference, consider the other aspects of safe mode mentioned before. Do you have hardware acceleration enabled in normal mode? If you do, disable it. Do you use the default theme in normal mode? If not, use the default theme and see if it helps. Do you have a userChrome.css or userContent.css file in the chrome subfolder of the profile folder?

Thanks: No hardware acceleration; using default theme; not using Chrome, and couldn't find a chrome subfolder under ~/Library/Thunderbird/Profiles.

I have uninstalled McAfee and not (so far) suffered the crash.

Update:

Am getting the crashing still, after upgrading to TB 60.50.0. At this point, I have deleted all AV software. TB 60.5.0 seems less stable than 60.4.0.

I was not getting crashes in safe-mode. The only add-on I'm running is lightning, but crashing exists with lightning disabled.

Any suggestions welcome.

This isn't a suggestion for a solution, but it is one more data point for the TB development team: I was experiencing freezes several times per day. I was using Avast for anti-virus and general protection.

I uninstalled Avast. (I did a complete uninstall.) The next day TB froze once more. But there have been no freezes since then.

It seems that TB doesn't get along well with most anti-virus software. This seems like a problem with TB that should be fixed.

This is one of now dozens of crash reports submitted to Apple:

Date/Time: 2019-02-06 22:54:57 -0500 End time: 2019-02-06 22:54:59 -0500 OS Version: Mac OS X 10.14.2 (Build 18C54) Architecture: x86_64 Report Version: 27

Data Source: Stackshots Shared Cache: 0x24b84000 42B93EB1-59B9-31B5-A5B2-FBE6E38DFE09 Shared Cache: 0 3B04C446-660F-35CE-ADD5-E5F3BBB0C34D

Command: thunderbird Path: /Applications/Thunderbird.app/Contents/MacOS/thunderbird Identifier: org.mozilla.thunderbird Version: 60.5.0 (60.5.0) Parent: launchd [1] PID: 548

Event: hang Duration: 2.09s (process was unresponsive for 22 seconds before sampling) Steps: 21 (100ms sampling interval)

Hardware model: MacBookPro9,2 Active cpus: 4

Time Awake Since Boot: 680s

Fan speed: 1994 rpm

Timeline format: stacks are sorted chronologically Use -i and -heavy to re-report with count sorting

Heaviest stack for the main thread of the target process:

 21  ??? (XUL + 36360001) [0x10e557f41]
 21  -[NSApplication(NSEvent) _nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 1362 (AppKit + 106754) [0x7fff4c536102]
 21  _DPSNextEvent + 997 (AppKit + 111459) [0x7fff4c537363]
 21  _BlockUntilNextEventMatchingListInModeWithFilter + 64 (HIToolbox + 42344) [0x7fff4e27c568]
 21  ReceiveNextEventCommon + 618 (HIToolbox + 42987) [0x7fff4e27c7eb]
 21  RunCurrentEventLoopInMode + 293 (HIToolbox + 43701) [0x7fff4e27cab5]
 21  CFRunLoopRunSpecific + 467 (CoreFoundation + 241334) [0x7fff4eff2eb6]
 21  __CFRunLoopRun + 1226 (CoreFoundation + 243155) [0x7fff4eff35d3]
 21  __CFRunLoopDoSources0 + 195 (CoreFoundation + 245804) [0x7fff4eff402c]
 21  __CFRunLoopDoSource0 + 108 (CoreFoundation + 360831) [0x7fff4f01017f]
 21  __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17 (CoreFoundation + 360921) [0x7fff4f0101d9]
 21  ??? (XUL + 36167249) [0x10e528e51]
 21  -[NSView removeFromSuperview] + 167 (AppKit + 615683) [0x7fff4c5b2503]
 21  -[NSView _setWindow:] + 2315 (AppKit + 612374) [0x7fff4c5b1816]
 21  -[NSSurface setWindow:] + 53 (AppKit + 3495945) [0x7fff4c871809]
 21  -[NSSurface _disposeSurface] + 132 (AppKit + 3496844) [0x7fff4c871b8c]
 21  -[NSNotificationCenter postNotificationName:object:userInfo:] + 66 (Foundation + 72315) [0x7fff5136ca7b]
 21  _CFXNotificationPost + 854 (CoreFoundation + 59145) [0x7fff4efc6709]
 21  -[_CFXNotificationRegistrar find:object:observer:enumerator:] + 1804 (CoreFoundation + 62564) [0x7fff4efc7464]
 21  ___CFXNotificationPost_block_invoke + 87 (CoreFoundation + 685585) [0x7fff4f05f611]
 21  _CFXRegistrationPost + 398 (CoreFoundation + 651997) [0x7fff4f0572dd]
 21  ___CFXRegistrationPost_block_invoke + 63 (CoreFoundation + 652220) [0x7fff4f0573bc]
 21  __CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 12 (CoreFoundation + 652354) [0x7fff4f057442]
 21  CGLClearDrawable + 44 (OpenGL + 28901) [0x7fff591620e5]
 21  _pthread_mutex_firstfit_lock_slow + 226 (libsystem_pthread.dylib + 5303) [0x7fff7c4bb4b7]
 21  __psynch_mutexwait + 10 (libsystem_kernel.dylib + 15990) [0x7fff7c405e76]
*21  psynch_mtxcontinue + 0 (pthread + 10095) [0xffffff7f82c9d76f]

Process: thunderbird [548] UUID: BF6CBA35-D3F3-3A45-9A7E-CBC388DD773F Path: /Applications/Thunderbird.app/Contents/MacOS/thunderbird Architecture: x86_64 Parent: launchd [1] UID: 502 Footprint: 309.51 MB Start time: 2019-02-06 22:54:57 -0500 End time: 2019-02-06 22:54:59 -0500 Num samples: 21 (1-21) CPU Time: 0.031s (63.4M cycles, 14.1M instructions, 4.48c/i) Note: Unresponsive for 22 seconds before sampling Note: 1 idle work queue thread omitted

 Thread 0x1618             DispatchQueue 1           21 samples (1-21)         priority 46 (base 46)
 <thread QoS user interactive (requested user interactive), process unclamped, process received importance donation from WindowServer [216], IO tier 0>
 21  ??? (XUL + 36360001) [0x10e557f41] 1-21
   21  -[NSApplication(NSEvent) _nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 1362 (AppKit + 106754) [0x7fff4c536102] 1-21
     21  _DPSNextEvent + 997 (AppKit + 111459) [0x7fff4c537363] 1-21
       21  _BlockUntilNextEventMatchingListInModeWithFilter + 64 (HIToolbox + 42344) [0x7fff4e27c568] 1-21
         21  ReceiveNextEventCommon + 618 (HIToolbox + 42987) [0x7fff4e27c7eb] 1-21
           21  RunCurrentEventLoopInMode + 293 (HIToolbox + 43701) [0x7fff4e27cab5] 1-21
             21  CFRunLoopRunSpecific + 467 (CoreFoundation + 241334) [0x7fff4eff2eb6] 1-21
               21  __CFRunLoopRun + 1226 (CoreFoundation + 243155) [0x7fff4eff35d3] 1-21
                 21  __CFRunLoopDoSources0 + 195 (CoreFoundation + 245804) [0x7fff4eff402c] 1-21
                   21  __CFRunLoopDoSource0 + 108 (CoreFoundation + 360831) [0x7fff4f01017f] 1-21
                     21  __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17 (CoreFoundation + 360921) [0x7fff4f0101d9] 1-21
                       21  ??? (XUL + 36167249) [0x10e528e51] 1-21
                         21  -[NSView removeFromSuperview] + 167 (AppKit + 615683) [0x7fff4c5b2503] 1-21
                           21  -[NSView _setWindow:] + 2315 (AppKit + 612374) [0x7fff4c5b1816] 1-21
                             21  -[NSSurface setWindow:] + 53 (AppKit + 3495945) [0x7fff4c871809] 1-21
                               21  -[NSSurface _disposeSurface] + 132 (AppKit + 3496844) [0x7fff4c871b8c] 1-21
                                 21  -[NSNotificationCenter postNotificationName:object:userInfo:] + 66 (Foundation + 72315) [0x7fff5136ca7b] 1-21
                                   21  _CFXNotificationPost + 854 (CoreFoundation + 59145) [0x7fff4efc6709] 1-21
                                     21  -[_CFXNotificationRegistrar find:object:observer:enumerator:] + 1804 (CoreFoundation + 62564) [0x7fff4efc7464] 1-21
                                       21  ___CFXNotificationPost_block_invoke + 87 (CoreFoundation + 685585) [0x7fff4f05f611] 1-21
                                         21  _CFXRegistrationPost + 398 (CoreFoundation + 651997) [0x7fff4f0572dd] 1-21
                                           21  ___CFXRegistrationPost_block_invoke + 63 (CoreFoundation + 652220) [0x7fff4f0573bc] 1-21
                                             21  __CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 12 (CoreFoundation + 652354) [0x7fff4f057442] 1-21
                                               21  CGLClearDrawable + 44 (OpenGL + 28901) [0x7fff591620e5] 1-21
                                                 21  _pthread_mutex_firstfit_lock_slow + 226 (libsystem_pthread.dylib + 5303) [0x7fff7c4bb4b7] 1-21
                                                   21  __psynch_mutexwait + 10 (libsystem_kernel.dylib + 15990) [0x7fff7c405e76] 1-21
                                                    *21  psynch_mtxcontinue + 0 (pthread + 10095) [0xffffff7f82c9d76f] (blocked by pthread mutex owned by thunderbird [548] thread 0x1651) 1-21

 Thread 0x162e             21 samples (1-21)         priority 31 (base 31)
 <thread QoS default (requested default), process unclamped, process received importance donation from WindowServer [216], IO tier 0>
 21  thread_start + 13 (libsystem_pthread.dylib + 9237) [0x7fff7c4bc415] 1-21
   21  _pthread_start + 70 (libsystem_pthread.dylib + 25199) [0x7fff7c4c026f] 1-21
     21  ??? (XUL + 54082722) [0x10f63eca2] 1-21
       21  mach_msg_trap + 10 (libsystem_kernel.dylib + 4474) [0x7fff7c40317a] 1-21
        *21  ipc_mqueue_receive_continue + 0 (kernel + 1651312) [0xffffff8000393270] 1-21

 Thread 0x163e             Thread name "Gecko_IOThread"                        21 samples (1-21)         priority 31 (base 31)
 <thread QoS default (requested default), process unclamped, process received importance donation from WindowServer [216], IO tier 0>
 21  kevent + 10 (libsystem_kernel.dylib + 30486) [0x7fff7c409716] 1-21
  *21  ??? (kernel + 6974736) [0xffffff80008a6d10] 1-21

 Thread 0x1640             Thread name "Socket Thread"                         21 samples (1-21)         priority 31 (base 31)
 <thread QoS default (requested default), process unclamped, process received importance donation from WindowServer [216], IO tier 0>
 21  __select + 10 (libsystem_kernel.dylib + 34218) [0x7fff7c40a5aa] 1-21
  *21  ??? (kernel + 7163104) [0xffffff80008d4ce0] 1-21

 Thread 0x1641             Thread name "JS Watchdog" 21 samples (1-21)         priority 31 (base 31)
 <thread QoS default (requested default), process unclamped, process received importance donation from WindowServer [216], IO tier 0>
 21  ??? (<ABF4F665-7B46-3D37-92DE-875FD3B4451B> + 1390669) [0x109f5384d] 1-21
   21  __psynch_cvwait + 10 (libsystem_kernel.dylib + 18398) [0x7fff7c4067de] 1-21
    *21  psynch_cvcontinue + 0 (pthread + 19278) [0xffffff7f82c9fb4e] 1-21

 Thread 0x1642             Thread name "JS Helper"   21 samples (1-21)         priority 31 (base 31)
 <thread QoS default (requested default), process unclamped, process received importance donation from WindowServer [216], IO tier 0>
 21  thread_start + 13 (libsystem_pthread.dylib + 9237) [0x7fff7c4bc415] 1-21
   21  _pthread_start + 70 (libsystem_pthread.dylib + 25199) [0x7fff7c4c026f] 1-21
     21  ??? (<C039A933-37F2-364B-A720-E3F48804B276> + 55772) [0x109b0f9dc] 1-21
       21  __psynch_cvwait + 10 (libsystem_kernel.dylib + 18398) [0x7fff7c4067de] 1-21
        *21  psynch_cvcontinue + 0 (pthread + 19278) [0xffffff7f82c9fb4e] 1-21

The freezing always occurs immediately after sending a message, but of course not after every message.

Any help will be appreciated.

An update on this problem:

This is not AV software related; it persists with ALL AV software removed.

The problem seems to occur when I try to read a new message while TB is trying to send the previous message. It seems there's a conflict that TB can't get over.

I'm using TB in IMAP configuration, with SMTP outgoing server.

Is there a possibility that there are conflicting security layers in the outgoing and incoming server that cause the freeze?

Thanks.

Just to provide an extra data point on this problem. (I'm the original poster.) I uninstalled all anti-virus software, and that didn't solve the problem. (Not just deactivated AV, but completely uninstalled it.) And the previous post rings a bell. The problem (the freezes) seem to occur when I have just sent a message and then I'm starting to read a new message. Looks like a bug in TB, unrelated to AV or Lightning or any other external factors.

I haven't experienced the issue of freezing just after sending a message, but I suppose it could happen with IMAP accounts if copying (uploading) to the IMAP Sent folder causes a delay in reading (downloading) a new message. Make sure you don't have 'Place a copy in' checked in the Copies & Folders section of Account Settings if the mail provider automatically copies sent messages to Sent, e.g. gmail, outlook.com/hotmail/live accounts.

If the freezing is caused by possible corruption in the mail folders, I'd be inclined to create a 2nd, fresh profile with Profile Manager, add one account, and see if it behaves differently. It may seem a hassle, but it's the best way to test issues like this. Besides, a new profile often eliminates a lot of problems caused by accumulated 'profile rot'.

To start PM, close TB, Winkey+R, type thunderbird.exe -p There is a similar step for OS X. Each profile can be run independently, and mail, contacts, calendars etc. can be transferred over if the new profile performs better.