Technical Tip: Error on FortiSwitch GUI 'Forbidden You don't have permission to access this resource. Reason: Cannot perform Post-Handshake Authentication'

[laltuzar]

Description	This article describes how to fix the error appearing from time to time to users who upgraded FortiSwitches to 7.4.0 or earlier and started to get the error: 'Forbidden You don't have permission to access this resource. Reason: Cannot perform Post-Handshake Authentication'
Scope	FortiSwitch OS 7.4.0 or above.
Solution	Disable strong crypto, then reboot the FortiSwitch: config system global set strong-crypto disable end If the issue persists, try to set the FortiSwitch TLS version to 1/1/1.2 as follows: config system web set https-ssl-versions tlsv1-1 tlsv1-2 end For Firefox, it is possible to fix it in 'about:config', and set 'security.tls.enable_post_handshake_auth' to 'true'. This procedure might help also for errors where the GUI is accessible, The user can log in successfully and the dashboard is shown correctly but when navigating through the GUI to other menus, there is an error as shown below. User can log in correctly Dashboard is shown correctly Issue after trying to navigate through GUI