Pale Moon forum

In an effort to narrow down what might either be a Pale Moon bug, an extension bug/conflict, or a misconfiguration, I tried to run "palemoon --ProfileManager" from a terminal (to see if the issue reproduced on a blank profile on the same install without having to close my main profile's session)... and instead of the Profile Manager window, I got a new Pale Moon window for my currently running session. Running "palemoon -P" produced the same behavior, but running "palemoon --new-instance --ProfileManager" produced the profile manager as expected.

It seems like having the "--new-instance" flag be implied when either "--ProfileManager" or "-P" without an argument is specified might be more desirable behavior.

Sorry, but no.
The profile manager should not be launched when the browser is already running. This could easily lead to issues with profile in use errors (and resulting confusion) or even profile corruption depending on the situation. The "remote" behaviour is desired by default.

Just use Profile Switcher and optionally set it to run at startup so you can choose which profile to start with if frequently juggling multiple profiles is your thing^*. I use it because I have 2 additional ones - one for extension development and one fresh one for testing extensions before deployment as well as for broken websites.

* - which is not a great idea in practice.

First off, this thread is misfiled as profile functions are provided by the platform.

Regardless, No change will be made to established behavior of the Profile Manager.

Why? Because the Profile Manager's first duty is to Manage Profiles as in Creation and Selection in single instance mode as it was designed to operate in.

Running multiple profiles at the same time is NOT recommended for reasons I have explained in the past including those stated by Moonchild. If you do you should run with no-remote as Moonchild said though it is not ever a default and must be specified. You also likely should never specify profile by cli but use the Profile Manager ui to make the selection.

As a matter of intrest, adhoc profiles launched and not registered with the Profile Manager as used when you do mach run after compiling is also normally out of scope as well.

new-instance, however, is an internal mode designed to operate with e10s leftovers and the primitive and barely implemented about:profiles incarnation.

And this boys and girls is why about:profiles should be removed from the platform or be modified to be informational only. This is also why my extension despite being modified from the more powerful Communicator Profile Manager (used with my applications with identical functionality of the Toolkit Profile Manager but can be invoked anytime) does not have Managing functions included but only single instance switching. Which means the extension is safer for broad usership with the target applications and users.

For the record, my applications assume a level of technical skill and understanding that is not an implied standard among every Pale Moon or Basilisk user. As most are former Firefox users whom have been abused and kept in the dark about the technology they employ and tend to continue that indoctrinated mindset. EVEN WITH the abundance and wealth of technical information all over this forum and other resources.

tl;dr Just because something is there and just because Mozilla went on to adopt the Chrome channel profile setup and also the profile-as-a-service model of which theirs stems from experimental prototypes still existant in UXP doesn't mean you should be messing with it without deep understanding of how it works even if you THINK you do. As evidenced by the fact I had to write this post.