redirect mismatch, drop

[AEK]

Hello

I have some traffic blocked with the following message. Any idea what it means?

msg=" redirect mismatch, drop"

Logs from GUI.

Something also strange for me is that the source interface is "unknown0", and I don't have any interface of this name.

Any idea?

[dbu]

Hi @AEK 

When a packet comes to a FortiGate and FortiOS and it can't find an existing session for it, although it is expected that it has to be already in place it shows unknown0 as source interface. 

Have a look here for more information: 
https://community.fortinet.com/t5/FortiGate/Technical-Tip-Interface-unknown-0-in-traffic-logs/ta-p/1...

[AEK]

Thanks dbu

What about "redirect mismatch, drop"? What does it stand for? Why it is not a message just like "session not found"?

[dbu · Accepted solution]

Regarding the message  "redirect mismatch, drop" It means that an old session already existed in the browser and the new request is dropped. 
It can be disabled it with : 
Config system global

 set strict-dirty-session-check disable

end