In the case of the launch of the portable Firefox (ESR 52.2.0) in command line mode,
it is impossible to redirect the native output of the browser console (Firefox.exe) from the launcher (FirefoxPortable.exe) by typing the following command line:
C:> E: /FirefoxPortableESR52.2.0/FirefoxPortable.exe 2&1> dump.txt
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FirefoxPortableESR52.2.0 can't redirect message of console (window.dump) to a file
October 13, 2017 - 9:16am
#1
FirefoxPortableESR52.2.0 can't redirect message of console (window.dump) to a file
You're redirecting the output of the launcher, not Firefox itself. What you want to accomplish is not possible via the launcher in its current state. It would need to be specifically added as a feature.
Additionally, Firefox ESR 52 doesn't support headerless mode. It was introduced in Firefox 56.
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