I use Firefox with PDM more than 7 years.
If it is necessary to save the page - I use the *.mht format - saving in one file (archive).
There are no problems at the same time.
For this purpose I use Adding - "Mozilla Archive Format" or "UnMHT".
But it works at Firefox - x32 bit, on new - х64 bit versions from 5.11.2018 - this support will be stopped - it is recommended to use Addition of "Save Page WE".
I have many files *.mht - and not only in PDM - that I will do - now cannot tell. I tried something - now definitely I do not remember.
There are some options, but they not really suit me.
Now about failures - the reason most likely in scripts of Java and other files - to which logically react an antivirus and settings of the browser.
Besides - Firefox shall be set up on start with the rights of the administrator and process (including the shortcut menu) is added to antivirus exceptions.
It is also perhaps necessary to disconnect the Defender of Windows or DEP.
I tried options with other browsers, with a regret of suitable options did not find.
To save the page in the *.html format - you should not even try is hundreds of files with different extensions.
If someone has any other variants and sentences - it interests me too.
Also in the vault settings - on the Adding of Files tab it is necessary to add extension of "mht".
Most likely the reason of failures also in impossibility of automatic adding of not specified extensions of files.
Yes I have the same issue. The program comes when you want to upload or save any file that forces it to open up file explorer. I can't even right click to save pictures or like you said upload files. I always get a popup that says "failed to connect to vault" then Firefox crashes. Edge, Chrome, Opera, all work just fine it's just firefox, the one I use the most.
Welcome to the club..it seems we are the only few that have this...
That is the exact same issue I have...and yes very annoying as firefox is my primary browser...
And it is possible to learn what Firefox version? And what Windows?
I do not remember the exact reason, but I use only old versions of Firefox (unfortunately).
Did not try to set something from old versions?
I decided thus solved a problem with XnView - new versions were less functional.
One more option - a problem in some security settings of the program, Windows, antivir/firewall softs.
There is an opportunity to check something by other machine or Virtual machine?
Latest version of Firefox, Win10 Pro vr 1803, SW 2018 SP3.0. If you happen to recall what the fix was, there's at least 2 user that could use a tip or two.
I have checked Firefox of 47.0.2 (x64) - any problems with pdm SW-2018 SP3.
The truth I checked in Win-7x64 where I have established Comodo Internet Security that it is very convenient for settings.
Without problems I have save and I have opened "html" of file + the folder (with referenced files). Check/Uncheck, Open - without problems.
I didn't try to keep in one file (mht-arhiv type) because there is no time - but has to work (it is necessary to establish addition).
From this I draw a simple conclusion - a problem in the Windows settings.
In Windows 10 - it is rather difficult to adjust a firewall (in comparison with Windows7 + Comodo). Except a firewall there is still a service of Protection of the software, and settings of Firefox.
All this can glitch if there are no necessary settings or exceptions.
Probably a problem in it.
For a start, it is necessary to add processes and/or the Firefox and Windows Exlorer applications to exceptions.
Firefox.exe - to adjust on start with the rights of the administrator.
It is possible - to add the account of the current user on a label of local view Vault.
The reasons can be much.
Also some Windows updates can be the cause.