Technical Tip: Unable to log in to FortiGate GUI after upgrading to v7.6.4 with post-login banner

[ssanga]

Description	This article describes an issue where an administrator fails to login to GUI using either local or remote user accounts after upgrading to firmware version 7.6.4, when post-login banner is enabled.
Scope	FortiGate v7.6.4.
Solution	After upgrading to version 7.6.4, administrators are unable to log in to the GUI using either local or remote user accounts. After entering valid credentials, the GUI displays an authentication failure message. This issue is triggered only when post-login banner is enabled. Logging in through the CLI continues to work normally, even when the post-login banner is enabled. This issue has been resolved in: v7.6.5 (scheduled to be released in November 2025) v8.0.0 (scheduled to be released in March 2026) These timelines for firmware release are estimated and may be subject to change. Workaround: Disable the post-login banner using the following CLI commands. config system global     set post-login banner disable end