user.js: Netflix Error F7121-1331 on Mac/Linux [solved: RFP's HTTP Header is spoofed as Windows & NF no longer chills] [1610762]

You are right. Netflix works when I report the real user agent when RFP is enabled.

I think we have some progress here, but unless @tomrittervg actions it (or feeds it to a first bug apprentice), it’ll never happen and languish at P5, and that’s understandable, not because it’s a difficult patch (it’s pretty simple IMO), but because RFP is for TB, and TB don’t really want this (and it’s moot given DRM is blocked and AFAICT this is about the only instance of HTTP Header spoofing causing an issue), and IDK if tom et al really want an extra code path/divergence

so IDK what will happen ¯\_(ツ)_/¯

Okay so I set the OS as macos and FF version to 91. RFP is enabled with user_pref("privacy.resistFingerprinting", true); (That is the only pref in the user js for this profile). The user agent now is : Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14.3; rv:91.0) Gecko/20100101 Firefox/91.0

edit - That is the user agent in the http header

And netflix works

So I don’t know what the answer is. Personally I think we could do away with the version spoofing, at least on Firefox. If TBA wanted to keep the version changes only for flag days, then that could also be coded

I will be happy to test anything if you need me to.

OK. So maybe it is to do with the user agent? One one way to tell would be

• in a new profile (no user.js), make sure Netflix works
• then clear everything (Ctrl-SHift-Del)
• enable RFP and retest Netflix - it should Error F7121-1331
• then clear everything (Ctrl-SHift-Del)
• then install a user agent extension [1] and “lie” about yourself being Firefox the real user agent (or close enough)
  • by that I mean, if you are FF96 on Linux, then show that
  • test what the agent says first - e.g. at TZP
  • test Netflix - if it works then it’s not RFP per se, but NF being dicks and not using feature detection

[1] Am trying to find an easy to use extension but they’re all a bit shit TBH, I guess Canvas Blocker is the easiest

• CB Settings > APIs > untick everything except Navigator API (note you can’t untick canvas)
  • tick Navigator API
  • click Open (for navigator settings)
  • etc, you can just clilck your OS + FF and tghe version should already be {real Firefox version}

after some guggling the interwebs I would like to know if this fixes it

• Settings > General > Performance >
  • uncheck Use recommended performance settings
  • this then will show you another options - check it - Use hardware acceleration when available
• Restart
• Test
• Undo changes

If this solves it, then we have an answer as to why it happens, but I don’t recommend you change default perf settings, hence why I said to undo the changes