Avast and Firefox SEC_ERROR_UNKNOWN_ISSUER

[REDACTED]

Hello,

The Avast caused error SEC_ERROR_UNKNOWN_ISSUER in my Firefox 60.0 (64 bits). The problem resolved after disable https scanning.

Article about problem
https://support.mozilla.org/en-US/kb/troubleshoot-SEC_ERROR_UNKNOWN_ISSUER

[Asyn]

- Which Avast..? (Free/Pro/IS/Premier)
- Which version..?
- OS..? (32/64 Bit..? - which SP/Build..?)
- Other security related software installed..?

[REDACTED]

Avast Free 18.4.2338
Windows 10 x64 - 1709 Build 16299.431
Yes, COMODO Firewall.

The article cited include Avast in list of softwares that cause the error in Firefox. The COMODO Firewall not influence.

Thank you!

[Asyn]

1. Download Avast Free Antivirus: https://files.avast.com/iavs9x/avast_free_antivirus_setup_offline.exe
2. Follow instructions: https://www.avast.com/uninstall-utility (Run this tool for all prior installed Avast versions..!!)
3. Reinstall Avast with the downloaded installer from point 1.
4. Reboot.

[Martin00]

I have the same problem with the latest version 18.4.2338 on Windows 10 and Firefox 60.0.
Weird thing is that it is happening after my system runs for a few hours...

[Asyn]

I have the same problem with the latest version 18.4.2338 on Windows 10 and Firefox 60.0.
Weird thing is that it is happening after my system runs for a few hours...

Are you also running Comodo FW..?

[Martin00]

Nope, just avast.

[Asyn]

OK, see if the clean reinstall (Reply #3) helps.

[REDACTED]

Hello,

Thank you! The problem is solved now.

[REDACTED]

I'll wait, if the problem appear again I return here.

[Asyn]

Hello,

Thank you! The problem is solved now.

You're welcome.

[Martin00]

Another problem - avastclear wont open in the safe mode...

[Hopper15]

I had to disable https scanning like the OP.

[Martin00]

I had to disable https scanning like the OP.

If you think making yourself more vulnerable is a good choice than why not. I on the other hand like to be protected any way I can.


After another reboot it has let me to use that tool.

Reinstalled the program and now Firefox crashes cause Avast cant install its addon; it shows problems with email account certificates (all 5 email accounts on different sites), my scanning jobs are gone and instead shows this on the scanning options:
And those are just the things I have noticed right away.

[Asyn]

Please stay on topic, else start your own thread.