for several years now I'm using three local installations of FF Portable on my PC.
I installed (extracted) all three of them to different directories (which I have full control over). I'm using them all at the same time for different purposes. Ofc FirefoxPortable.ini has the AllowMultipleInstances=true set. Up to version 117.0.1 everything was fine.
However I upgraded to version 118 today and now only the very first instance I start opens as expected. When I try to open the second or third instance they instead just open a new window of the first instance.
To make myself more clear, let's say I have three Firefox Portable installations called "Main", "B" and "C". Up to 117.0.1 I was able to open and run Main, B and C at the same time. They opened their own instance/window at their last opened position. They worked independently. All was good.
With v118, when I open Main for example, Main opens as expected. But when I try to additionally start B it just opens another window of Main. Same for C and so on. Same with starting B or C first. So after I closed all windows and made sure no instance of Firefox is running, starting B opens B just as expected. But when I try to additionally start Main or C they just open new windows of B.
So whatever I try now, I can only start one instance of FF Portable. All other instances I start just open windows of the first instance.
I still have Backups of 117.01 and they still work as expected. But as soon as I upgrade them to 118 they they brake as described above.
I'm on Windows 10, version 22H2 (19045.3448) is that even matters.
All FF Portable installations are in different directories I have full control over (but also tried different directories just to make sure).
FirefoxPortable.ini has the AllowMultipleInstances=true set for all three of them.
I'm using the English (British) versions of FF Portable (c6973f2428e7f893c6c36fd520e01f4c69ae89a60df09d22da727835d3add285).