After closing everything else, force quit the computer.

Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options) key, and then starting Firefox. Is the problem still there?

While still in Safe Mode,

Type about:support in the address bar and press Enter. Under the main banner, press the button; Copy Text To Clipboard.. Then in the reply box at the bottom of this page, do a right click in the box and select Paste. This will show us your system details. No Personal Information Is Collected.

https://support.mozilla.org/en-US/kb/firefox-hangs-or-not-responding

https://support.mozilla.org/kb/Firefox+is+already+running+but+is+not+responding

Hi,

Thanks for replying.

It still happens in Safe Mode.

I don't see a 'Copy Text To Clipboard' button in about:config.

Thanks

Kneale said

I don't see a 'Copy Text To Clipboard' button in about:config.

FredMcD said

Type about:support in the address bar and press Enter.

Sorry, I misread that.

Application Basics

Name: Firefox Version: 43.0.4 Build ID: 20160105164030 Update Channel: release User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:43.0) Gecko/20100101 Firefox/43.0 Multiprocess Windows: 0/1 (default: false) Safe Mode: true

Crash Reports for the Last 3 Days

Report ID: bp-698dd773-3e1f-469d-a110-8531c2160123 Submitted: 9 hours ago

All Crash Reports

Extensions

Name: Virtual Keyboard Version: 14.0 Enabled: false ID: vkbd@kaspersky.com

Graphics

Asynchronous Pan/Zoom: none Device ID: 0x0166 GPU Accelerated Windows: 0/1 Basic Supports Hardware H264 Decoding: No; Vendor ID: 0x8086 windowLayerManagerRemote: false AzureCanvasBackend: skia AzureContentBackend: quartz AzureFallbackCanvasBackend: none AzureSkiaAccelerated: 0

Important Modified Preferences

accessibility.typeaheadfind.flashBar: 0 browser.cache.disk.capacity: 358400 browser.cache.disk.filesystem_reported: 1 browser.cache.disk.hashstats_reported: 1 browser.cache.disk.smart_size.first_run: false browser.cache.frecency_experiment: 3 browser.download.importedFromSqlite: true browser.places.smartBookmarksVersion: 7 browser.sessionstore.upgradeBackup.latestBuildID: 20160105164030 browser.startup.homepage_override.buildID: 20160105164030 browser.startup.homepage_override.mstone: 43.0.4 browser.urlbar.suggest.searches: true browser.urlbar.userMadeSearchSuggestionsChoice: true dom.apps.reset-permissions: true dom.mozApps.used: true extensions.lastAppVersion: 43.0.4 gfx.blacklist.direct2d: 3 gfx.crash-guard.glcontext.appVersion: 43.0.4 gfx.crash-guard.glcontext.deviceID: 0x0166 gfx.crash-guard.status.glcontext: 2 media.gmp-gmpopenh264.abi: x86_64-gcc3-u-i386-x86_64 media.gmp-gmpopenh264.lastUpdate: 1452555291 media.gmp-gmpopenh264.version: 1.5.3 media.gmp-manager.buildID: 20160105164030 media.gmp-manager.lastCheck: 1453566955 media.youtube-ua.override.to: 43 network.cookie.prefsMigrated: true network.predictor.cleaned-up: true places.database.lastMaintenance: 1452606749 places.history.expiration.transient_current_max_pages: 104858 plugin.disable_full_page_plugin_for_types: application/pdf plugin.importedState: true privacy.sanitize.migrateFx3Prefs: true privacy.sanitize.timeSpan: 0 storage.vacuum.last.index: 1 storage.vacuum.last.places.sqlite: 1452606749

Important Locked Preferences

JavaScript

Incremental GC: true

Accessibility

Activated: false Prevent Accessibility: 0

Library Versions

NSPR Expected minimum version: 4.10.10 Version in use: 4.10.10

NSS Expected minimum version: 3.20.2 Basic ECC Version in use: 3.20.2 Basic ECC

NSSSMIME Expected minimum version: 3.20.2 Basic ECC Version in use: 3.20.2 Basic ECC

NSSSSL Expected minimum version: 3.20.2 Basic ECC Version in use: 3.20.2 Basic ECC

NSSUTIL Expected minimum version: 3.20.2 Version in use: 3.20.2

Experimental Features

Thanks

bp-698dd773-3e1f-469d-a110-8531c2160123

Signature libsystem_kernel.dylib

RapportUtil1.dylib = Rapport

libsystem_pthread.dylib =  ? Word for Mac

GeForceGLDriver

libsystem_c.dylib = ? Word for Mac

libdispatch.dylib =  ? Word for Mac

OpenGL

libsystem_notify.dylib = unknown

libGPUSupportMercury.dylib

libsystem_platform.dylib = unknown

libGL.dylib = unknown

libsystem_kernel.dylib =  ? Word for Mac

GLEngine

This is for Sumo's Related Bugs 1237957 RESOLVED DUPLICATE GLContext is disabled due to a previous crash

Disable / update Rapport

What should I do?

Thanks

Try to disable WebGL by setting webgl.disabled to <strike>false</strike> true on the about:config page.

You can open the about:config page via the location/address bar. You can accept the warning and click "I'll be careful" to continue.

• http://kb.mozillazine.org/about:config

It's already set to false.

Do you mean set it to true?

Thanks

(I am still in Safe Mode btw)

Yes, that should be true to disable WebGL. Sorry for the confusion.

Did you try that?

Hi, no the problem still persists.

I can't even shut down my laptop after I've quit Firefox, I have to use the power off button.

I want you to try this. Start the computer normally. Let it run itself for a few minutes so that everything gets loaded. After, shut it down.

Start your Computer in safe mode with networking. Then start Firefox. Try Safe web sites. Is the problem still there?

Starting The Computer In Safe Mode;
Free Online Encyclopedia

No, the problem isn't there in Safe Mode. Firefox quits normally.

Thanks

Did you already update to Firefox 44.0?

Do you have security software on your Mac that could cause this issue?

Updating now, I don't have any security software installed.

I am having the same problem. It usually occurs only after Firefox has just been updated. After holding the power button on my Mac (to force a shutdown), I can bring Firefox back up and it will shutdown correctly.

Kneale said

I don't have any security software installed.

That is very dangerous. Many websites have been infected over the years.