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New Contributor

SSL deep inspection and ERR_CONNECTION_RESET error.


we facing a problem many many websites not working with error "ERR_CONNECTION_RESET"

sites became available when I disable ssl deep inspection (ssl certificate is deployed on all client computers)

How could I troubleshot this?

Contributor II

Contributor II



This is probably due to a bug and Fortinet has distributed the following information to partners:


Access to Websites blocked using SSL inspection -Bug ID 750551


There appears to be an ongoing issue with the certificate chain of a root certificate authority (ISRG Root X1). This issue will affect all vendors of SSL-inspection products whether deep or just certificate inspection is in use.


This issue has been reported and we will keep you posted on the developments.


Currently, the workarounds are:

Make a backup. At the top right > click your profile > Config > backup

1. Use flow-based web filtering. Note: the firewall policy will need to be in flow-mode as well for this to work.

2. Alternatively in the SSL Inspection Profile > Invalid Certificate > "Custom" and Allow "Expired Certificate" in the interim. (This should be used with caution).


For more info, Please checkout the following links:



Further information on the stale certificate:


Hope that helps

New Contributor II

Issue on 6.4.5 temporarily resolved by following workaround: 1: verify cert bundle is v28 -> diag autoupdate versions -> execute update-now 2: apply DNS blackhole workaround: -> config system dns-database -> edit "1" -> set domain "" -> config dns-entry -> edit 1 -> set hostname "apps" -> set ip -> next -> end 3a: flow-mode: -> diag ips share clear cert_verify_cache 3b: proxy-mode: ->:diag test app wad 99


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