Troubleshooting Tip: FortiSwitch E flag 'error_reason':'The legal characters are numbers (0-9), letters(a-z,A-z) and special characters - and _'

[pprince]

Description	This article describes the configuration sync error (E flag) in FortiSwitches and how to troubleshoot the issue. For an example, see the following command output: FortiGate # execute switch-controller get-conn-status SWITCH-ID VERSION STATUS       FLAG  ADDRESS JOIN-TIME NAME S448DNTXXXXXXXXX  Authorized/Up E  172.15.12.5 Fri May 9 12:51:12 2025 NAME-FS-448D FLOOR $- FortiGate # execute switch-controller get-sync-status all FortiLink interface : TRUNK SWITCH (NAME) STATUS CONFIG MAC-SYNC HTTP-UPGRADE S448DNTXXXXXXXXX (NAME-FS-448D FLOOR $-) Up Error - - [1] command: https:// 172.15.12.5/api/v2/cmdb/system/global payload: { "json": { "hostname": "NAME-FS-448D FLOOR $-" } } result : { "http_method":"PUT", "status":"error", "http_status":400, "vdom":"root", "path":"system", "name":"global", "cmdb-index":"906", "cmdb-checksum":"579982470908089437", "serial":"S448DNTXXXXXXXXX ", "version":"v7.0.7", "build":96, "timestamp":"2025-05-09T10:52:53Z", "error_reason":"The legal characters are numbers (0-9), letters(a-z,A-z) and special characters - and _"
Scope	FortiSwitch v7.4.0 and above.
Solution	From FortiSwitch version 7.4.0 and above, the managed FortiSwitch can be renamed; on earlier versions, the serial number of the FortiSwitch was the name of the FortiSwitch. To rename the FortiSwitch, see the FortiSwitch 7.4.0 FortiLink Guide. The naming of FortiSwitch follows a naming rule. The allowed characters are a-z, A-Z, 0-9, _, -, . and $, with some special rules for the special characters -, _ . and $. Namely, they cannot be put in the beginning, and only . and $ can be put at the end. See bug ID 882815 in the FortiOS 7.4.0 release notes.Keep the FortiGate and FortiSwitch up-to-date with the recommended firmware, as per the compatibility matrix.