Technical Tip: The issue of ERR_CERT_DATE_INVALID when accessing websites via FortiProxy
| Description | This article describes the issue of ERR_CERT_DATE_INVALID when clients are accessing some specific websites via FortiProxy:
   When examining the certificate further, it showed that the certificate learned from FortiProxy was already expired:
 
However, the actual certificate from FortiProxy is still valid:
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| Scope | FortiProxy. |
| Solution | Running the packet sniffer in FortiProxy, showed that when FortiProxy was communicating with an upstream device (Sophos Firewall) in TLS handshake, the certificate was encrypted in TLS 1.3 packets. So it should be checked further on the Sophos side.
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