I have forgotten to mention: I have tried to start FF on internal and Nvidia Graphics - no difference and I have tried to install and run FF w/o virus protection system ...

Let’s do a full clean re-install;

Note: Firefox comes in three or more folders on all computers. They are;

Maintenance: (Programs Folder) <Windows Only> Firefox itself: (Programs Folder) And two folders in the profile of each user on the computer for each Firefox profile for that user.

If you remove the Firefox folder, the user profiles would not be affected.

Download Firefox For All languages And Systems {web link}

Firefox ESR; Extended Support Release {web link}

Beta, Developer, Nightly versions https://www.mozilla.org/en-US/firefox/channel/desktop/

Install Older Version Of Firefox {web link}

Save the file. Then Close Firefox.

Using your file browser, open the Programs Folder on your computer.

Windows: C:\Program Files C:\Program Files (x86) Note: Check Both Folders

Mac: Open the "Applications" folder. https://support.mozilla.org/en-US/kb/how-download-and-install-firefox-mac

Linux: Check your user manual. If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it. See Install Firefox on Linux; https://support.mozilla.org/en-US/kb/install-firefox-linux

If you downloaded and installed the binary package from the Firefox download page, simply remove the folder Firefox in your home directory. http://www.mozilla.org/firefox#desktop ++++++++++++++++++++++++++++ Look for, and remove any Mozilla or Firefox program folders. Do not remove the Mozilla Thunderbird folder if there is one.

Do Not remove any profile folders.

After rebooting the computer, run a registry scanner if you have one. Then run the installer. +++++++++++++++++++++++++++ If there is a problem, start your Computer in safe mode and try again.

How to Start all Computers in Safe Mode; {web link} Free Online Encyclopedia

Hi FredMcD Thank you for the instructions.

I have now found out the following:

FF v84 runs in window10's safe mode but not in the normal mode!

I have downloaded the FFv83 which runs as expected (created a new profile for that to be sure, that the profile is not to blame). After executing the Update to FFv84, it crashs again - seems that something in FF got incompatible with my system.

It could be the work of one of your add-ons, or it could be Hardware Acceleration. How to disable Hardware Acceleration {web link}

Type about:addons<enter> in the address bar to open your Add-ons Manager. Hot key; <Control> (Mac=<Command>) <Shift> A)

In the Add-ons Manager, on the left, select Extensions. Disable a few add-ons, then Restart Firefox.

Some added toolbar and anti-virus add-ons are known to cause Firefox issues. Disable All Of them.

If the problem continues, disable some more (restarting FF). Continue until the problem is gone. After, you know what group is causing the issue. Re-enable the last group ONE AT A TIME (restarting FF) until the problem returns.

Once you think you found the problem, disable that and re-enable all the others, then restart again. Let us know who the suspect is, detective.

To disable the hardware acceleration did not solved the problem. And as I wrote earlier, I did a cean installation of FF83 w/o any installed AddOn and that update failed too.

Start your Computer in safe mode with network support. Then start Firefox. Try Secure websites. Is the problem still there?

http://encyclopedia2.thefreedictionary.com/Linux+Safe+Mode Starting Any Computer In Safe Mode; Free Online Encyclopedia

There is no problem in safe mode. FF84 runs w/o problem (even with running AddOns). Seems to be an incompatibility with my system. Is there a way to analyze the dump file at AppData\Local\CrashDumps ?

I downloaded the WinDeb Previwe tool from MS and evaluated the last dmp file. Seems to be a null pointer access error. This was the output from analyze -v:

CONTEXT: (.ecxr) rax=00007ffa45b613e0 rbx=000000f91cde5000 rcx=0000000000000000 rdx=0000000000000000 rsi=0000000000000081 rdi=0000000000000000 rip=0000000000000000 rsp=000000f91d5feff8 rbp=0000000000000000

r8=0000000000000000  r9=000000f91d5ff038 r10=00000fff48b6c27c

r11=ffffffffffffffff r12=000000f91d5ff1b0 r13=0000000000000000 r14=0000000000000000 r15=00007ffa45b613e0 iopl=0 nv up ei pl zr na po nc cs=0033 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010246 00000000`00000000 ??  ??? Resetting default scope

EXCEPTION_RECORD: (.exr -1) ExceptionAddress: 0000000000000000

  ExceptionCode: c0000005 (Access violation)
 ExceptionFlags: 00000000

NumberParameters: 2

  Parameter[0]: 0000000000000008
  Parameter[1]: 0000000000000000

Attempt to execute non-executable address 0000000000000000

PROCESS_NAME: firefox.exe

EXECUTE_ADDRESS: 0

FAILED_INSTRUCTION_ADDRESS: +0 00000000`00000000 ??  ???

ERROR_CODE: (NTSTATUS) 0xc0000005 - Die Anweisung in 0x%p verwies auf Arbeitsspeicher bei 0x%p. Der Vorgang %s konnte im Arbeitsspeicher nicht durchgef hrt werden.

EXCEPTION_CODE_STR: c0000005

EXCEPTION_PARAMETER1: 0000000000000008

EXCEPTION_PARAMETER2: 0000000000000000

STACK_TEXT: 000000f9`1d5feff8 00007ffa`6c67f746  : 000000f9`1cde5000 00000000`00000000 00000000`00000081 00000000`00000000 : 0x0 000000f9`1d5ff000 00007ffa`6c6841c2  : 0000cbb4`af192b9f 00007ffa`6d580304 000000f9`1d5ff330 00007ffa`6d580464 : user32!fnHkINLPCWPSTRUCTW+0xd6 000000f9`1d5ff0b0 00007ffa`6d580464  : 000000f9`1d5ff148 000000f9`1d5ff218 00007ffa`6ad21f24 00000090`000000e8 : user32!__fnINLPCREATESTRUCT+0xa2 000000f9`1d5ff110 00007ffa`6ad21f24  : 00007ffa`6c667dc1 ffffffff`ffff0000 00000000`40000a00 00000000`0000c03b : ntdll!KiUserCallbackDispatcherContinue 000000f9`1d5ff218 00007ffa`6c667dc1  : ffffffff`ffff0000 00000000`40000a00 00000000`0000c03b 000000f9`1d5ff2e0 : win32u!NtUserCreateWindowEx+0x14 000000f9`1d5ff220 00007ffa`6c6679b4  : 00000276`0000000a 00000276`00000000 00000000`00000000 00000000`88000000 : user32!VerNtUserCreateWindowEx+0x211 000000f9`1d5ff5b0 00007ffa`6c6677f2  : 00000000`80000000 00000000`00000000 000000f9`1d5ff8e0 00000276`17b74960 : user32!CreateWindowInternal+0x1b4 000000f9`1d5ff710 00007ffa`6d17e726  : 00000276`197c9078 00000000`00000000 00000276`00000000 00007ffa`6d178190 : user32!CreateWindowExW+0x82 000000f9`1d5ff7a0 00007ffa`6d0ed3b3  : 00000000`00000000 00000000`00000002 000000f9`1d5ff8e0 00007ffa`6d0c8cb6 : combase!InitMainThreadWnd+0x56 000000f9`1d5ff810 00007ffa`6d0edec8  : 00000276`17b74960 000000f9`1d5ff8f9 00000276`197c9078 00000276`17b5c490 : combase!ThreadFirstInitialize+0x1e7 000000f9`1d5ff860 00007ffa`6d0edd3b  : 00000276`17f04001 00000000`00000000 00000000`00000002 00000000`00000000 : combase!_CoInitializeEx+0x174 000000f9`1d5ff960 00007ffa`0324f571  : 000000f9`1d5ff9f0 00007ffa`041ad8e6 000000f9`1d5ffaa8 00007ffa`48f714fd : combase!CoInitializeEx+0x4b 000000f9`1d5ff9b0 00007ffa`070597e3  : 00000276`17f040d0 00000000`00000000 00000276`17b69dd0 00007ffa`48f66283 : xul!XRE_GetBootstrap+0xb7b1 000000f9`1d5ffa80 00007ffa`07059d53  : 00000276`17b69dd0 00007ffa`48f66283 00000000`00000001 00007ffa`6d533bd0 : xul!workerlz4_maxCompressedSize+0x13e853 000000f9`1d5ffb40 00007ff7`2f5c15a1  : 00000000`0000002c 00000000`00000000 00000276`17b637c0 00000276`17f00080 : xul!workerlz4_maxCompressedSize+0x13edc3 000000f9`1d5ffca0 00007ff7`2f61b838  : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : firefox!Ordinal0+0x15a1 000000f9`1d5ffec0 00007ffa`6b857c24  : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : firefox!TargetNtUnmapViewOfSection+0xb088 000000f9`1d5fff00 00007ffa`6d54d4d1  : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : kernel32!BaseThreadInitThunk+0x14 000000f9`1d5fff30 00000000`00000000  : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : ntdll!RtlUserThreadStart+0x21

SYMBOL_NAME: win32u!NtUserCreateWindowEx+14

MODULE_NAME: win32u

IMAGE_NAME: win32u.dll

STACK_COMMAND: ~0s ; .ecxr ; kb

FAILURE_BUCKET_ID: SOFTWARE_NX_FAULT_c0000005_win32u.dll!NtUserCreateWindowEx

OS_VERSION: 10.0.18362.1

BUILDLAB_STR: 19h1_release

OSPLATFORM_TYPE: x64

OSNAME: Windows 10

IMAGE_VERSION: 10.0.18362.1237

FAILURE_ID_HASH: {51a386b0-1fb8-16df-c033-d1b8b5e52c49}

Followup: MachineOwner

I found and downloaded the WinDeg Preview tool from MS.

Seems to be an access to an inaccessible memory address. Here is the output of !analyze -v:

CONTEXT: (.ecxr) rax=00007ffa45b613e0 rbx=000000f91cde5000 rcx=0000000000000000 rdx=0000000000000000 rsi=0000000000000081 rdi=0000000000000000 rip=0000000000000000 rsp=000000f91d5feff8 rbp=0000000000000000

r8=0000000000000000  r9=000000f91d5ff038 r10=00000fff48b6c27c

r11=ffffffffffffffff r12=000000f91d5ff1b0 r13=0000000000000000 r14=0000000000000000 r15=00007ffa45b613e0 iopl=0 nv up ei pl zr na po nc cs=0033 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010246 00000000`00000000 ??  ??? Resetting default scope

EXCEPTION_RECORD: (.exr -1) ExceptionAddress: 0000000000000000

  ExceptionCode: c0000005 (Access violation)
 ExceptionFlags: 00000000

NumberParameters: 2

  Parameter[0]: 0000000000000008
  Parameter[1]: 0000000000000000

Attempt to execute non-executable address 0000000000000000

PROCESS_NAME: firefox.exe

EXECUTE_ADDRESS: 0

FAILED_INSTRUCTION_ADDRESS: +0 00000000`00000000 ??  ???

ERROR_CODE: (NTSTATUS) 0xc0000005 - Die Anweisung in 0x%p verwies auf Arbeitsspeicher bei 0x%p. Der Vorgang %s konnte im Arbeitsspeicher nicht durchgef hrt werden.

EXCEPTION_CODE_STR: c0000005

EXCEPTION_PARAMETER1: 0000000000000008

EXCEPTION_PARAMETER2: 0000000000000000

STACK_TEXT: 000000f9`1d5feff8 00007ffa`6c67f746  : 000000f9`1cde5000 00000000`00000000 00000000`00000081 00000000`00000000 : 0x0 000000f9`1d5ff000 00007ffa`6c6841c2  : 0000cbb4`af192b9f 00007ffa`6d580304 000000f9`1d5ff330 00007ffa`6d580464 : user32!fnHkINLPCWPSTRUCTW+0xd6 000000f9`1d5ff0b0 00007ffa`6d580464  : 000000f9`1d5ff148 000000f9`1d5ff218 00007ffa`6ad21f24 00000090`000000e8 : user32!__fnINLPCREATESTRUCT+0xa2 000000f9`1d5ff110 00007ffa`6ad21f24  : 00007ffa`6c667dc1 ffffffff`ffff0000 00000000`40000a00 00000000`0000c03b : ntdll!KiUserCallbackDispatcherContinue 000000f9`1d5ff218 00007ffa`6c667dc1  : ffffffff`ffff0000 00000000`40000a00 00000000`0000c03b 000000f9`1d5ff2e0 : win32u!NtUserCreateWindowEx+0x14 000000f9`1d5ff220 00007ffa`6c6679b4  : 00000276`0000000a 00000276`00000000 00000000`00000000 00000000`88000000 : user32!VerNtUserCreateWindowEx+0x211 000000f9`1d5ff5b0 00007ffa`6c6677f2  : 00000000`80000000 00000000`00000000 000000f9`1d5ff8e0 00000276`17b74960 : user32!CreateWindowInternal+0x1b4 000000f9`1d5ff710 00007ffa`6d17e726  : 00000276`197c9078 00000000`00000000 00000276`00000000 00007ffa`6d178190 : user32!CreateWindowExW+0x82 000000f9`1d5ff7a0 00007ffa`6d0ed3b3  : 00000000`00000000 00000000`00000002 000000f9`1d5ff8e0 00007ffa`6d0c8cb6 : combase!InitMainThreadWnd+0x56 000000f9`1d5ff810 00007ffa`6d0edec8  : 00000276`17b74960 000000f9`1d5ff8f9 00000276`197c9078 00000276`17b5c490 : combase!ThreadFirstInitialize+0x1e7 000000f9`1d5ff860 00007ffa`6d0edd3b  : 00000276`17f04001 00000000`00000000 00000000`00000002 00000000`00000000 : combase!_CoInitializeEx+0x174 000000f9`1d5ff960 00007ffa`0324f571  : 000000f9`1d5ff9f0 00007ffa`041ad8e6 000000f9`1d5ffaa8 00007ffa`48f714fd : combase!CoInitializeEx+0x4b 000000f9`1d5ff9b0 00007ffa`070597e3  : 00000276`17f040d0 00000000`00000000 00000276`17b69dd0 00007ffa`48f66283 : xul!XRE_GetBootstrap+0xb7b1 000000f9`1d5ffa80 00007ffa`07059d53  : 00000276`17b69dd0 00007ffa`48f66283 00000000`00000001 00007ffa`6d533bd0 : xul!workerlz4_maxCompressedSize+0x13e853 000000f9`1d5ffb40 00007ff7`2f5c15a1  : 00000000`0000002c 00000000`00000000 00000276`17b637c0 00000276`17f00080 : xul!workerlz4_maxCompressedSize+0x13edc3 000000f9`1d5ffca0 00007ff7`2f61b838  : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : firefox!Ordinal0+0x15a1 000000f9`1d5ffec0 00007ffa`6b857c24  : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : firefox!TargetNtUnmapViewOfSection+0xb088 000000f9`1d5fff00 00007ffa`6d54d4d1  : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : kernel32!BaseThreadInitThunk+0x14 000000f9`1d5fff30 00000000`00000000  : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : ntdll!RtlUserThreadStart+0x21

SYMBOL_NAME: win32u!NtUserCreateWindowEx+14

MODULE_NAME: win32u

IMAGE_NAME: win32u.dll

STACK_COMMAND: ~0s ; .ecxr ; kb

FAILURE_BUCKET_ID: SOFTWARE_NX_FAULT_c0000005_win32u.dll!NtUserCreateWindowEx

OS_VERSION: 10.0.18362.1

BUILDLAB_STR: 19h1_release

OSPLATFORM_TYPE: x64

OSNAME: Windows 10

IMAGE_VERSION: 10.0.18362.1237

FAILURE_ID_HASH: {51a386b0-1fb8-16df-c033-d1b8b5e52c49}

Followup: MachineOwner

I called for more help. As a test, disable your protection programs.

I disabled all protection: FF84 keeps crashing.

For completeness: Windows and all drivers are up to date

https://support.mozilla.org/en-US/kb/firefox-slow-how-make-it-faster

https://support.mozilla.org/en-US/kb/firefox-uses-too-many-cpu-resources-how-fix

https://support.mozilla.org/en-US/kb/firefox-uses-too-much-memory-ram

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

https://support.mozilla.org/en-US/kb/firefox-takes-long-time-start-up

https://support.mozilla.org/en-US/kb/quick-fixes-if-your-firefox-slows-down

MemTest LAST UPDATED : 12/04/2020 Could you please run a tool from http://memtest.org/ in order to check the integrity of your RAM?

You will need a thumb or disk drive to install it on.

Do you let Windows handle the page file or did you set a fixed size ? If you use a fixed size for the page file then try the former and let Windows handle the page file. How to determine the appropriate page file size for 64-bit versions of Windows {web link}

I run the windows' internal memory test (mdsched.exe) w/o an error. The page file is handled by Windows and not set to fixed. Currently no other program crashes.

Keep us posted.