hello, first please make sure that the date, time & timezone are set correctly on your system. if this doesn't solve the issue (or it is already set properly), a solution depends on the individual circumstances:

• what is the error code shown when you click on advanced on that error page?
• please also give us more information about the error by clicking on the error code, copying the text to the clipboard and then pasting it here into a reply in the forum.

thank you!

Fehlercode: SEC_ERROR_UNKNOWN_ISSUER

Date, Time and timezone are correct.

please in addition provide the info as it's described in my second bullet point and shown in the screenshot. thank you.

https://www.google.com/search?q=google&ie=utf-8&oe=utf-8&client=firefox-b

Der Zertifikat-Aussteller der Gegenstelle wurde nicht erkannt.

HTTP Strict Transport Security: false HTTP Public Key Pinning: true

Zertifikatskette:

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MIIDYzCCAkugAwIBAgIIdZ5TWClO40IwDQYJKoZIhvcNAQELBQAwVjEZMBcGA1UE CgwQQU8gS2FzcGVyc2t5IExhYjE5MDcGA1UEAwwwS2FzcGVyc2t5IFdlYiBBbnRp LVZpcnVzIENlcnRpZmljYXRpb24gQXV0aG9yaXR5MB4XDTA2MTIxOTA3NTc0MVoX DTI2MTIxNDA3NTc0MVowVjEZMBcGA1UECgwQQU8gS2FzcGVyc2t5IExhYjE5MDcG A1UEAwwwS2FzcGVyc2t5IFdlYiBBbnRpLVZpcnVzIENlcnRpZmljYXRpb24gQXV0 aG9yaXR5MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEArx8y2DE9lqPK cJxWYOZ/NtP4lAt9CRK+AwsTwEvt0jdxkfj3dnKBdDcE+uXkTdTy5uFWwl9I34UU 5FSF39MiuQ6L+dxSGlyrPFk3DWvI9mi+Cyba48rsKavSb0LPX17WuC76QGJu6IJP 6Dbntc6QWogQd7cJSfYbr7MUnbT+gnLRMMTVVh2tJ9bYDQFOP6hYRePw6A4FYnfO lvufFy8ZcwUqTwBcgvdclwDATLxnzNpzSV/zdCsptNmv/GBfa3dDqy7MW0PkGeD+ OdvfyGXYm//Czlhtkg2HF5EwDXs53fKvIHUSSvJDF37Os+2RMgFBRofIXoHysEll Bg5YT0K7swIDAQABozUwMzAPBgNVHRMBAf8EBTADAQH/MAsGA1UdDwQEAwICBDAT BgNVHSUEDDAKBggrBgEFBQcDATANBgkqhkiG9w0BAQsFAAOCAQEAoxtnTiIeqs6P zdOIVtOj2DZ5a7hCpsm9t/swi8Xcak2UWZjNL/KyHh377KOHa58JExm38SaEAtN4 4o5iIVCKzRB68SMM6qRBJ9dUNG7QDKWKtP7iZ9SErYyzvgq6O1Z5kVt/UjMwLt1T 6HiEXis7/w2WMQrb8vh4nh7yU/mtkGQaExTOrDwCWPxkiJLqhT/NGKVoDyCH+dG9 QHVJiLPiB1HCn45y+nLv61qoo//ulOYYYM6wgxINQ96+FXKe0sIFwBInwi5X/eIP vZEEe956LAPasHEkIlrhRdEEZDeRZReNUsJZxI+Bc/gPpw3t6GvBQEN085ATQk7o mKHSOtGGlQ==

thank you, so it is apparently kaspersky meddling with your secure connections in the browser and causing these errors - please refer to the section about kaspersky in How to troubleshoot security error codes on secure websites to fix this.