Firefox Portable

I need to access a corporate application that has a web interface and a Java applet.

I read that Firefox 52 and later don't allow the Java plugin anymore. So I installed Firefox Portable 51.0.1 into C:\users\username\Downloads\Firefox_51.0.1_Portable\FirefoxPortable. Then I copied the FirefoxPortable.ini file from the Other\Source directory and put it in the same directory as FirefoxPortable.exe. I edited the file to have the following:

AllowMultipleInstances=true
AlwaysUse32Bit=true

Every time I exit (window close, ALT+F4) Firefox Quantum, a few seconds later the crash reporter pops up. Nothing problematic about Firefox itself, just does this upon exiting. (Submitting the crash report always fails, too, so it's not worth bothering with.)

I just X out of the crash reporter and I haven't been worried about it, but thought I'd drop a note here.

Windows 10 Pro 1703 (work computer), 64-bit. Install path is default, and it's an upgrade. I've had Portable Firefox on my drive since I don't even know when.

I'm running a browser extension (or should I say "add on"?) which requires the presence of a so called "companion app".
In a non-portable environment such an app has to be installed in the main OS, as well as the browser itself.

I'm wondering whether there is a way to "install" such an app inside the FF Portable's folder, in order to carry it around together with the browser, in a USB key or similar device.

PS. I searched, before posting, for similar questions but did not find any.

How can one update from the ESR (52) Firefox to the newest (57) one?

How can one exclude Firefox from updating? So when three is an update PortableApps shall not install it.

hello,
I want to set LocalHomepage in FirefoxPortable.ini (same directory as FirefoxPortable.exe).So,i set the line LocalHomepage=http://www.google.com; il does not work.
is there anything else to do ?

Hello. I don't want to update my main Firefox installation yet because several add-ons I use are legacy without replacements. But I'd like to segue to FF 57 and instead of creating a new Portable Apps directory it would be nice to use a 2nd profile installation in my regular PA directory for the transition. I know I can use the beta but betas are betas.

Have a nice day!

Is it ipossible to launch the "Desktop Firefox" and Portable Firefox (52.2.0) in the same time?
If I start "Desktop Firefox" then I start Portable Firefox I get an error message pop up:
"Another instance of Firefox is already running. Please close other instances of Firefox before launching Mozilla Firefox, Portable Edition"
Is there a solution?

I have Firefox v57.0 "installed" as a portable app. In the "App" folder there is a "Firefox" folder and a "Firefox64" folder. I only ever use the 64-bit version so is it possible to completely delete the "Firefox" folder? It's kind of strange in a way. The "Firefox" folder contains 113 files. The "Firefox64" folder contains 112 files. What is the extra file in the "Firefox" folder?