I can't remember whether this started after a Windows 10 update or a
Firefox update....

Several times a day when I try to open an htm file (for which Firefox is
the default application) Firefox opens to a blank page - nothing in the
address bar. Then, when I try to quit Firefox, I get the message
"Firefox is already running but is not responding. The old Firefox
process must be closed before opening a new window."

Closing Firefox using the button below the error message sometimes helps
- but usually I have to go to Task Manager and remove all the instances
of Firefox that have somehow been listed there.

Anyone else have this problem? Any suggestions how I can get rid of it?

malone wrote:
>
> I can't remember whether this started after a Windows 10 update or a
> Firefox update....
>
> Several times a day when I try to open an htm file (for which Firefox is
> the default application) Firefox opens to a blank page - nothing in the
> address bar. Then, when I try to quit Firefox, I get the message
> "Firefox is already running but is not responding. The old Firefox
> process must be closed before opening a new window."
>
> Closing Firefox using the button below the error message sometimes helps
> - but usually I have to go to Task Manager and remove all the instances
> of Firefox that have somehow been listed there.
>
> Anyone else have this problem? Any suggestions how I can get rid of it?

Firefox is a small empire unto itself.

https://wiki.mozilla.org/Security/Sandbox/Process_model

The things you see in Task Manager are not mere "user opens page,
system starts another process". Even when it's doing nothing
at all, it opens five to eight processes, and inside each
process could be hundreds of threads. The processes talk to
one another with things like named pipes. Interprocess
communications is not a free lunch. The developers pay the
price for being cheeky.

The process model also suggests a "harvesting model". When you
want to kill Firefox, killing one process should cause the other
processes to "get the message". Now, observe it sometime and see
just how poorly this works. It's as slow... as... molasses...
A good OS would have "killpg" or Kill Process Group with a PGID
for an argument. Killing a Child and waiting for this to ripple up
to the Parent At The Top, hmmm. Not so good if using
timeouts on named pipes or something, as a detection mechanism.
I don't think Windows has "fork", making this particularly
difficult.

You see, the things they want to do, may make sense in Unix
or Linux or macOS, but Windows has not been strong in these areas.
The end result, is the product looks like "sloppy seconds"
on Windows. It's absolute shite while shutting down.

*******

They seem to feel here, that binding the program to a file type,
plays a certain havoc with the program behavior. But perhaps
this is just bad paraphrasing on my part.

https://support.mozilla.org/en-US/kb/firefox-repeatedly-opens-empty-tabs-or-windows

That's all I found so far.

Paul

malone wrote:

> Anyone else have this problem? Any suggestions how I can get rid of it?

Start by checking if the problem still exists in trouble-shooting mode,
from the help menu ...

"Paul" <nospam@needed.invalid> wrote

| A good OS would have "killpg" or Kill Process Group with a PGID
| for an argument. Killing a Child and waiting for this to ripple up
| to the Parent At The Top, hmmm. Not so good...

But the whole point of separate processes is to actually run
separately. There's no parent or child. The parent should be
the MDI window with the chrome and children would be
tabs. If I start 2 Notepads I have 2 Notepad processes.
They have no business talking to each other.

And wasn't the whole point with FF processes to isolate for
security? So it sounds like they're "isolating" 1 house to clear
out bedbugs, but moving furniture and bedding between houses
at the same time. Don't tell me... it's for "improved user
experience", right? :)

"malone" <malone@nospam.net.nz> wrote

| Several times a day when I try to open an htm file (for which Firefox is
| the default application) Firefox opens to a blank page - nothing in the
| address bar. Then, when I try to quit Firefox, I get the message
| "Firefox is already running but is not responding. The old Firefox
| process must be closed before opening a new window."
|

I don't have an answer, but I wonder if you might have
done something like close a window that was in the middle
of downloading. Alternatively, if you routinely allow script
it's possible you could have a stuck window somewhere.
That's all I can think of.

I never use tabs and rarely have more than about 5 instances
open. But I know some people just don't bother to close windows.
They can end up with 150 websites loaded. Many of those sites
will reload periodically if you let them. That can get very
complicated.

On Sun, 20 Jun 2021 at 02:14:25, Paul <nospam@needed.invalid> wrote (my
responses usually follow points raised):
>malone wrote:
[]
>> Closing Firefox using the button below the error message sometimes
>>helps - but usually I have to go to Task Manager and remove all the
>>instances of Firefox that have somehow been listed there.
[]
>Firefox is a small empire unto itself.
[]
>The process model also suggests a "harvesting model". When you
>want to kill Firefox, killing one process should cause the other
>processes to "get the message". Now, observe it sometime and see
>just how poorly this works. It's as slow... as... molasses...
[]
>You see, the things they want to do, may make sense in Unix
>or Linux or macOS, but Windows has not been strong in these areas.
>The end result, is the product looks like "sloppy seconds"
>on Windows. It's absolute shite while shutting down.
[]
Just for interest: the ancient Firefox I run here (27.0.1!), which dates
from well before the multi-process model (it has one process open,
having been running for some days with twentysomething tabs open), still
takes a while to shut down - let me try: the window disappears within a
few seconds of my saying yes I do really want to close it, but the
process remains in task manager for ... about two and a half minutes.
(Comes back, to where it was, in about 30 seconds - I think about 15,
with the rest being the page on the open tab loading.)

Just thought you might be interested that it's not the multi-process
thing as such that's the cause - though I suspect the internal
operation's the same as you describe.
--
J. P. Gilliver. UMRA: 1960/<1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

"Bother," said Pooh, as Eeyore sneezed the crack all over Owl.

malone wrote:
>
> I can't remember whether this started after a Windows 10 update or a
> Firefox update....
>
> Several times a day when I try to open an htm file (for which Firefox is
> the default application) Firefox opens to a blank page - nothing in the
> address bar. Then, when I try to quit Firefox, I get the message
> "Firefox is already running but is not responding. The old Firefox
> process must be closed before opening a new window."
>
> Closing Firefox using the button below the error message sometimes helps
> - but usually I have to go to Task Manager and remove all the instances
> of Firefox that have somehow been listed there.
>
> Anyone else have this problem? Any suggestions how I can get rid of it?

An active extension or plugin may be preventing shut down.
There are several million hits for the issue on Google.
Here is one to get you started on a possible fix:
https://support.mozilla.org/en-US/kb/firefox-already-running-not-responding#w_end-firefox-processes

On 21-Jun-2021 5:34 am, Paul in Houston TX wrote:
> malone wrote:
>>
>> I can't remember whether this started after a Windows 10 update or a
>> Firefox update....
>>
>> Several times a day when I try to open an htm file (for which Firefox
>> is the default application) Firefox opens to a blank page - nothing
>> in the address bar. Then, when I try to quit Firefox, I get the
>> message "Firefox is already running but is not responding. The old
>> Firefox process must be closed before opening a new window."
>>
>> Closing Firefox using the button below the error message sometimes
>> helps - but usually I have to go to Task Manager and remove all the
>> instances of Firefox that have somehow been listed there.
>>
>> Anyone else have this problem? Any suggestions how I can get rid of it?
>
> An active extension or plugin may be preventing shut down.
> There are several million hits for the issue on Google.
> Here is one to get you started on a possible fix:
> https://support.mozilla.org/en-US/kb/firefox-already-running-not-responding#w_end-firefox-processes
>
>

Thanks for that - and the other respondents' contributions. I don't have
any extensions or plugins.

I often play short .mp4 videos directly through Firefox and with my very
slow internet download (2Mbps) there's a lot of buffering and I often
abort before completion. I wonder whether that could cause the problem?

J. P. Gilliver (John) wrote:
> On Sun, 20 Jun 2021 at 02:14:25, Paul <nospam@needed.invalid> wrote (my
> responses usually follow points raised):
>> malone wrote:
> []
>>> Closing Firefox using the button below the error message sometimes
>>> helps - but usually I have to go to Task Manager and remove all the
>>> instances of Firefox that have somehow been listed there.
> []
>> Firefox is a small empire unto itself.
> []
>> The process model also suggests a "harvesting model". When you
>> want to kill Firefox, killing one process should cause the other
>> processes to "get the message". Now, observe it sometime and see
>> just how poorly this works. It's as slow... as... molasses...
> []
>> You see, the things they want to do, may make sense in Unix
>> or Linux or macOS, but Windows has not been strong in these areas.
>> The end result, is the product looks like "sloppy seconds"
>> on Windows. It's absolute shite while shutting down.
> []
> Just for interest: the ancient Firefox I run here (27.0.1!), which dates
> from well before the multi-process model (it has one process open,
> having been running for some days with twentysomething tabs open), still
> takes a while to shut down - let me try: the window disappears within a
> few seconds of my saying yes I do really want to close it, but the
> process remains in task manager for ... about two and a half minutes.
> (Comes back, to where it was, in about 30 seconds - I think about 15,
> with the rest being the page on the open tab loading.)
>
> Just thought you might be interested that it's not the multi-process
> thing as such that's the cause - though I suspect the internal
> operation's the same as you describe.

There are some nuances here.

Selecting "quit" from a program menu, is not the same
thing as Task Manager "kill".

In the "kill" case, the system harvests the executable. The resources
are freed. The RAM is returned to the system. Handles on open write
files are discarded, without the materials "committed" to the file system.

In the "menu quit" case, that's the "orderly" shutdown case. The program
can scan through its list of open handles, and decide what to do.
It might even decide, if it wants, to roll back some state info
to a consistent state before closing. This takes as long as it takes,
at the discretion of the designer.

My record here for Firefox hanging around, is around 12 hours I think,
when Firefox was "bugged" with some not-that-special javascript code.

Selecting quit is not all it's cracked up to be.

In the Firefox Quantum case, let us say you use Task Manager
and arbitrarily kill one of the processes. The named pipe goes
dead on one end. The other processes, which may have their own
idea of a ping running on the named pipes, might notice after
two seconds, that the subtending process is no longer responding.
Perhaps they can check that the PID is still valid. But the program
managed "harvesting", if the program decides this is a hint to
shut down, that takes a long time and a lot of dodgy logic,
to complete. I was not impressed by this, the times I've tested it.
Part of the fault for this, belongs to Windows, for never implementing
the infrastructure for this style of programming. Microsoft could have
invented a "fork()" or "execve()" call years ago, if they'd liked.

So when you kill one item on Firefox in the Quantum case, two
kinds of termination are involved. One process drops dead on the
spot. The remaining processes then have to decide amongst
themselves, whether the user is asking for termination or
the content has tipped over a multimedia container process.

There is probably some variant of kill, that kills all
processes named "firefox.exe" and perhaps that would be
a better way of immediately dropping the thing. But in situations
where you need immediate compliance, this is not going to
end well, because you're not really in control. All you can
do, is be part of a slow motion train wreck, and this is
hardly a good thing.

Paul

On 6/20/2021 3:07 PM, malone wrote:
> On 21-Jun-2021 5:34 am, Paul in Houston TX wrote:
>> malone wrote:
>>>
>>> I can't remember whether this started after a Windows 10 update or a
>>> Firefox update....
>>>
>>> Several times a day when I try to open an htm file (for which Firefox
>>> is the default application) Firefox opens to a blank page - nothing
>>> in the address bar. Then, when I try to quit Firefox, I get the
>>> message "Firefox is already running but is not responding. The old
>>> Firefox process must be closed before opening a new window."
>>>
>>> Closing Firefox using the button below the error message sometimes
>>> helps - but usually I have to go to Task Manager and remove all the
>>> instances of Firefox that have somehow been listed there.
>>>
>>> Anyone else have this problem? Any suggestions how I can get rid of it?
>>
>> An active extension or plugin may be preventing shut down.
>> There are several million hits for the issue on Google.
>> Here is one to get you started on a possible fix:
>> https://support.mozilla.org/en-US/kb/firefox-already-running-not-responding#w_end-firefox-processes
>>
>>
>
> Thanks for that - and the other respondents' contributions. I don't have
> any extensions or plugins.
>
> I often play short .mp4 videos directly through Firefox and with my very
> slow internet download (2Mbps) there's a lot of buffering and I often
> abort before completion. I wonder whether that could cause the problem?

I've seen this for well over a year, so it's not new. I think the
relevant part is "abort before completion", as FF will sometimes appear
to close, but leaves something that gives Windows the notion that it is
still active. I don't know whether it is that the app is actually still
running or just not closing properly.

--
best regards,

Neil

"Mayayana" <mayayana@invalid.nospam> wrote:

> "malone" wrote
>
>| Several times a day when I try to open an htm file (for which Firefox is
>| the default application) Firefox opens to a blank page - nothing in the
>| address bar. Then, when I try to quit Firefox, I get the message
>| "Firefox is already running but is not responding. The old Firefox
>| process must be closed before opening a new window."

> I never use tabs and rarely have more than about 5 instances
> open. But I know some people just don't bother to close windows.
> They can end up with 150 websites loaded.

Sound like that is talking about a smartphone.

The original poster obviously closes Firefox... "quit...closed...closing...
Firefox"

Neil wrote:

> malone wrote:
>> Paul in Houston TX wrote:
>>> malone wrote:

>>>> I can't remember whether this started after a Windows 10 update or a
>>>> Firefox update....
>>>>
>>>> Several times a day when I try to open an htm file (for which Firefox
>>>> is the default application) Firefox opens to a blank page - nothing
>>>> in the address bar. Then, when I try to quit Firefox, I get the
>>>> message "Firefox is already running but is not responding. The old
>>>> Firefox process must be closed before opening a new window."
>>>>
>>>> Closing Firefox using the button below the error message sometimes
>>>> helps - but usually I have to go to Task Manager and remove all the
>>>> instances of Firefox that have somehow been listed there.
>>>>
>>>> Anyone else have this problem? Any suggestions how I can get rid of
>>>> it?
>>>
>>> An active extension or plugin may be preventing shut down. There are
>>> several million hits for the issue on Google. Here is one to get you
>>> started on a possible fix:
>>> https://support.mozilla.org/en-US/kb/firefox-already-running-not-respon
>>> ding#w_end-firefox-processes

>> Thanks for that - and the other respondents' contributions. I don't
>> have any extensions or plugins.
>>
>> I often play short .mp4 videos directly through Firefox and with my
>> very slow internet download (2Mbps) there's a lot of buffering and I
>> often abort before completion. I wonder whether that could cause the
>> problem?
>
> I've seen this for well over a year, so it's not new. I think the
> relevant part is "abort before completion", as FF will sometimes appear
> to close, but leaves something that gives Windows the notion that it is
> still active. I don't know whether it is that the app is actually still
> running or just not closing properly.

The only similar thing I've noticed is that Firefox uses multiple volume
controls in Windows' "Volume Mixer" (as if anybody knows which Firefox volume
control goes with which Firefox tab/window) AND it doesn't bother closing
those controls (or windows has trouble closing them) when Firefox is closed.

Definitely buggy.

But since I use Macrium Reflect for backup after each time Windows is restored
and updated, programs have little/no chance of being corrupted like the
original poster's.

malone <malone@nospam.net.nz> wrote:

> I can't remember whether this started after a Windows 10 update or a
> Firefox update....
>
> Several times a day when I try to open an htm file (for which Firefox is
> the default application) Firefox opens to a blank page - nothing in the
> address bar. Then, when I try to quit Firefox, I get the message
> "Firefox is already running but is not responding. The old Firefox
> process must be closed before opening a new window."
>
> Closing Firefox using the button below the error message sometimes helps
> - but usually I have to go to Task Manager and remove all the instances
> of Firefox that have somehow been listed there.
>
> Anyone else have this problem? Any suggestions how I can get rid of it?

I might... Restore Windows, uninstall Firefox, install Firefox. See if the
problem still exists. Use Macrium Reflect's browse capability to restore
Firefox settings as needed.

If Firefox allows keeping settings when uninstalled, of course you could try
that first.

If successful, immediately make a fresh backup and you're in the clear.

"Life can be so easy... la la la"

John Doe wrote:

> I might... Restore Windows [correction, don't bother with the Windows
> restore first], uninstall Firefox, install Firefox. See if the problem
> still exists.

Uhg...
But you want to copy out your Firefox folders first. So you have access to
your most recent settings.