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Firefox doesn't load YouTube sidebar

  • 8 replies
  • 1 has this problem
  • 3 views
  • Last reply by Andros

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Yesterday I completely formatted my computer and when I tried opening Firefox today, I got the "sec_error_unknown_issuer" error. This is not the first time that happens, last time I formatted my PC I also got the same problem, and I fixed it by disabling Enterprise Roots in about:config. But whenever I try opening YouTube, the website it's completely ruined, the sidebar (where my subscriptions and playlist are located) doesn't load and neither does the videos from the bottom. Last time this happened, I completely gave up and switched to other browser, some months later without touching anything, I opened Firefox again and somehow it was loading the sidebar. But this time I dont want to wait again, and I don't know if it will "fix" by itself. I tried opening Firefox in safe mode and everything, and had no success.

Yesterday I completely formatted my computer and when I tried opening Firefox today, I got the "sec_error_unknown_issuer" error. This is not the first time that happens, last time I formatted my PC I also got the same problem, and I fixed it by disabling Enterprise Roots in about:config. But whenever I try opening YouTube, the website it's completely ruined, the sidebar (where my subscriptions and playlist are located) doesn't load and neither does the videos from the bottom. Last time this happened, I completely gave up and switched to other browser, some months later without touching anything, I opened Firefox again and somehow it was loading the sidebar. But this time I dont want to wait again, and I don't know if it will "fix" by itself. I tried opening Firefox in safe mode and everything, and had no success.
Attached screenshots

Chosen solution

I think I solved it. Apparently, I had to disable the proxys on Youtube!

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All Replies (8)

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  • MOZILLA_PKIX_ERROR_MITM_DETECTED
  • uses an invalid security certificate SSL_ERROR_BAD_CERT_DOMAIN
  • configured their website improperly

How to troubleshoot the error code "SEC_ERROR_UNKNOWN_ISSUER" on secure websites https://support.mozilla.org/en-US/kb/troubleshoot-SEC_ERROR_UNKNOWN_ISSUER


There is security software like Avast, Kaspersky, BitDefender and ESET that intercept secure connection certificates and send their own.

https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can

https://support.mozilla.org/en-US/kb/firefox-and-other-browsers-cant-load-websites

https://support.mozilla.org/en-US/kb/secure-connection-failed-firefox-did-not-connect

https://support.mozilla.org/en-US/kb/websites-dont-load-troubleshoot-and-fix-errors

What do the security warning codes mean

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Make sure you are not blocking content.

https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop also see https://blog.mozilla.org/security/2021/03/23/introducing-smartblock/

https://support.mozilla.org/en-US/kb/smartblock-enhanced-tracking-protection


Diagnose Firefox issues using Troubleshoot(Safe) Mode {web link}

A small dialog should appear. Click Start In Troubleshoot(Safe) Mode (not Refresh). Is the problem still there?


Many site issues can be caused by corrupt cookies or cache.

Warning ! ! This will log you out of sites you're logged in to. You may also lose any settings for that website.

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I had no success. I only use Windows Defender, so it's not an anti-virus problem. I disabled Hardware Acceleration already and it didn't worked. Youtube is completely broken, I can't watch videos or use any feature. Meanwhile when I test on Edge it does. It's a browser problem it seems

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Can you try Windows in Safe Mode?

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Chosen Solution

I think I solved it. Apparently, I had to disable the proxys on Youtube!

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Mark it as solved and keep it moving.  ;-))

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Andros117 said

I think I solved it. Apparently, I had to disable the proxys on Youtube!

That was very good work. Well Done. Please flag your last post as Solved Problem as this can help others with similar problems. Go to that post and click the 'Solved' button to its right.