FortiGate GUI Logs Out Immediately After Successful Login in EVE-NG

Hello Fortinet Community,

I have installed FortiGate-VM64 FortiOS 8.0.0 in my EVE-NG lab environment.

The FortiGate VM boots normally, and I am able to access the GUI login page.

Current Issue

I can successfully enter my credentials and the GUI appears to authenticate successfully. However, immediately after login, I am logged out and redirected back to the login page.

In other words:

1. Open FortiGate GUI.
2. Enter username and password.
3. Authentication appears successful.
4. GUI starts to load.
5. Immediately after that, the session is terminated and I am returned to the login screen.

Environment

• Platform: EVE-NG
• Device: FortiGate-VM64
• FortiOS: 8.0.0
• Build: 0167
• Image: FGT_VM64_KVM-v8.0.0.F-build0167-FORTINET.out.kvm.zip
• Deployment: KVM/EVE-NG

License Status

The FortiGate license is showing Up to Date / Active, so there does not appear to be an obvious licensing issue.

What I have checked

• FortiGate VM is booting normally.
• GUI is reachable.
• Username/password are accepted.
• License status shows up to date.
• The problem occurs immediately after successful GUI authentication.

I would like to understand what could cause the FortiGate GUI session to be immediately terminated after successful login.

Could this be related to:

• FortiOS 8.0.0 VM image?
• EVE-NG/KVM compatibility?
• System time/date or NTP?
• HTTPS/SSL certificate or browser session/cookie issue?
• Admin session settings?
• FortiGate VM resources?
• License/VM registration?
• Any known issue with FortiOS 8.0.0 build 0167?

Could someone please suggest the CLI commands or troubleshooting steps I should run to identify why the GUI session is being terminated immediately after login?

Thank you.