Thank you tumic for this suggestion. However, unfortunately it did not work. After carrying out the procedure described below, I got the following (slightly different from the previous, but essentially the same) error message:
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Secure Connection Failed
An error occurred during a connection to login.gmx.com. Peer's certificate issuer has been marked as not trusted by the user. (Error code: sec_error_untrusted_issuer)
The page you are trying to view cannot be shown because the authenticity of the received data could not be verified.
Please contact the website owners to inform them of this problem.
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The procedure I followed was:
- Log into administrator account
- Start Keychain Access
- Select System Roots: All items: Avast trusted CA
- File (or right-click) -> Export items: to Documents/Avast trusted CA.cer
- Quit Keychain Access
- Start Firefox (ver 39.0)
- Preferences -> Advanced -> Certificates
- [View certificates] -> Servers -> [Import]
Format:certificates
Select: Documents/Avast trusted CA.cer
[Open]
- [OK]
- Quit Firefox
- Log out of administrator account
- Restart
- Repeat procedure for user account (i.e export from the user's Keychain Access and import into user's Firefox)
Got the same error above in both the user and administrator accounts.
By the way, if I try to import "Avast trusted CA.cer" into "Your certificates" rather than "Servers", I get an error message:
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Alert: This personal certificate can't be installed because you do not own the corresponding private key which was created when the certificate was requested.
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Also, by the way, same errors occur when attempting to access
www.avast.com. Able to get here only by turning off Avast's web shield.