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New Contributor II

FortiOS 7.4.2 Bug Causes IPsec VPN Tunnel Phase 2 Instability

I have had many site-to-site IPsec tunnels working fine for several years until I upgraded to FortiOS 7.4.2. Shortly afterward, my tunnels began dropping connections on random Phase 2 connections. I have had to bring down the phases or entire tunnel to get traffic flowing again many times. I opened a ticket with Fortinet and had three technicians working with me at various times but none found a solution.


I finally downgraded to 7.4.1 and all my problems went away. There is obviously a bug in 7.4.2 and I hope Fortinet finds and acknowledges it and fixes it for the next release.

New Contributor II

What's the latest on this issue?  I keep getting bugged to upgrade to 7.4.3 but that's not happening until the site-to-site ipsec issue is resolved. Running a 200F here. 

New Contributor III

The bug still exists in 7.4.3 and it is my understanding that it will be fixed in 7.4.4 which should be released in the next couple weeks. This issue has Bug ID 1003830 and a workaround is provided in the release notes. Known issues | FortiGate / FortiOS 7.4.3 | Fortinet Document Library

New Contributor II

7.4.4 has been released and it looks as though this issue still has not been resolved. Known issues still seems to state to use the work around.


Just trying to keep this post updated. 

New Contributor II

Thanks for the update, it's indeed not fixed in 7.4.4

New Contributor

I also updated to 7.4.4 and still have the same problem. 

New Contributor II

I also updated to 7.4.4 and still have the same problem.
But we have the problem with many other things besides IPSec

Bruno Brustolin
Cloud Engineer
Bruno BrustolinCloud Engineer

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