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How to fully divide Firefox classic version and Developer edition?

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I've allowed to start DE while classic Firefox opened in my settings. I want to run them with different sync e-mail authorized, with different bookmarks, with different history for a different people use them. Is it possible? - I can't find right information about that possibility. Problem is that: 1) They can't work together with any settings (screenshot, trnslt: "FF already run, but doesn't responding. To open new window close it."), but actually it still responds; 2) I can't use one sync e-mail in FF and another one in DE. It changes to last authorization in both. So, what you recommend? Is it even possible to use them like different browsers for different people?

I've allowed to start DE while classic Firefox opened in my settings. I want to run them with different sync e-mail authorized, with different bookmarks, with different history for a different people use them. Is it possible? - I can't find right information about that possibility. Problem is that: 1) They can't work together with any settings (screenshot, trnslt: "FF already run, but doesn't responding. To open new window close it."), but actually it still responds; 2) I can't use one sync e-mail in FF and another one in DE. It changes to last authorization in both. So, what you recommend? Is it even possible to use them like different browsers for different people?

Chosen solution

You can have as many versions of Firefox as you want. I have six or seven. HOWEVER: Each version must use its own profile. This is because some things are not compatible.

Each must be started with special options on the command line. For example (all on one line);

C:\PROGRA~1\MOZILL~1\firefox.exe -no-remote -new-instance -new-window -P Firefox_v_57
.
https://developer.mozilla.org/en-US/docs/Mozilla/Command_Line_Options
.
Usage: C:\PROGRA~1\MOZILL~1\firefox.exe [ options ... ] [URL]
      where options include:
.
 -h or -help        Print this message.
 -v or -version     Print Firefox version.
 -P <profile>       Start with <profile>.
 -migration         Start with migration wizard.
 -ProfileManager    Start with ProfileManager.
 -no-remote         Do not accept or send remote commands; implies -new-instance.
 -new-instance      Open new instance, not a new window in running instance.
 -UILocale <locale> Start with <locale> resources as UI Locale.
 -safe-mode         Disables extensions and themes for this session.
 -console           Start Firefox with a debugging console.
 -jsconsole         Open the Error console.
 -browser           Open a browser window.
 -new-window  <url> Open <url> in a new window.
 -new-tab     <url> Open <url> in a new tab.
 -preferences       Open Options dialog.
 -search     <term> Search <term> with your default search engine.
 -setDefaultBrowser Set this app as the default browser.
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Chosen Solution

You can have as many versions of Firefox as you want. I have six or seven. HOWEVER: Each version must use its own profile. This is because some things are not compatible.

Each must be started with special options on the command line. For example (all on one line);

C:\PROGRA~1\MOZILL~1\firefox.exe -no-remote -new-instance -new-window -P Firefox_v_57
.
https://developer.mozilla.org/en-US/docs/Mozilla/Command_Line_Options
.
Usage: C:\PROGRA~1\MOZILL~1\firefox.exe [ options ... ] [URL]
      where options include:
.
 -h or -help        Print this message.
 -v or -version     Print Firefox version.
 -P <profile>       Start with <profile>.
 -migration         Start with migration wizard.
 -ProfileManager    Start with ProfileManager.
 -no-remote         Do not accept or send remote commands; implies -new-instance.
 -new-instance      Open new instance, not a new window in running instance.
 -UILocale <locale> Start with <locale> resources as UI Locale.
 -safe-mode         Disables extensions and themes for this session.
 -console           Start Firefox with a debugging console.
 -jsconsole         Open the Error console.
 -browser           Open a browser window.
 -new-window  <url> Open <url> in a new window.
 -new-tab     <url> Open <url> in a new tab.
 -preferences       Open Options dialog.
 -search     <term> Search <term> with your default search engine.
 -setDefaultBrowser Set this app as the default browser.
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That feature is coming in Firefox 67. It may be available right now in the Fx 66 Beta / Developer Edition.

https://support.mozilla.org/en-US/kb/dedicated-profiles-firefox-installation

Both Profiles will be separate from one another, and since Sync works at the Profile level different Sync / Firefox Accounts can be used.