Sandboxie-Start of FirefoxPortable requires Admin-Password

Stef, I hope you find this is a solution, for Firefox Portable with Sandboxie.  I also have Windows 1903 with the latest versions of Firefox Portable and 
Sandboxie.

I also have found if I try to run Firefox Portable in a sandbox from firefoxportable.exe in the root folder FirefoxPortable, it does not like Sandboxie, before opening the sandboxed browser, it will pop up the Windows message asking you to sign into your Admin account. 

Under the App folder, there are folders for Firefox and for Firefox64 which have "firefox.exe" for 32 or 64 bit version. I have changed my shortcut to Firefox portable to FirefoxPortable\App\Firefox64\firefox.exe and things are going very well. 

Steps to make a shortcut to the right application:

1.  In Sandboxie Control, create a sandbox called FFPORT or something like that.

2.  Choose Configuration - Windows Shell Integration - Add Shortcut icons

3.  Choose the FFPORT sandbox

4.  Ths Sandboxie Start Menu should appear.  Choose All files and folders

5.  Choose the drive then go down to FirefoxPortable\App\Firefox64\firefox.exe. if you have a 64 bit setup.  If not use:  FirefoxPortable\App\Firefox\firefox.exe  On my machine it does not show the application with the .exe extension.

6.  The shortcut should appear on your desktop.

Does this work for you?  

Best wishes, Doug

Stef, I hope you find this is a solution, for Firefox Portable with Sandboxie.  I also have Windows 1903 with the latest versions of Firefox Portable and 
Sandboxie.

I also have found if I try to run Firefox Portable in a sandbox from firefoxportable.exe in the root folder FirefoxPortable, it does not like Sandboxie, before opening the sandboxed browser, it will pop up the Windows message asking you to sign into your Admin account. 

Under the App folder, there are folders for Firefox and for Firefox64 which have "firefox.exe" for 32 or 64 bit version. I have changed my shortcut to Firefox portable to FirefoxPortable\App\Firefox64\firefox.exe and things are going very well. 

Steps to make a shortcut to the right application:

1.  In Sandboxie Control, create a sandbox called FFPORT or something like that.

2.  Choose Configuration - Windows Shell Integration - Add Shortcut icons

3.  Choose the FFPORT sandbox

4.  Ths Sandboxie Start Menu should appear.  Choose All files and folders

5.  Choose the drive then go down to FirefoxPortable\App\Firefox64\firefox.exe. if you have a 64 bit setup.  If not use:  FirefoxPortable\App\Firefox\firefox.exe  On my machine it does not show the application with the .exe extension.

6.  The shortcut should appear on your desktop.

Does this work for you?  

Best wishes, Doug