Skip to main content
WinterSnowYap
Staff
Staff
September 23, 2025

Troubleshooting Tip: FortiManager install preview 'Error: -999' due to invalid CLI syntax

  • September 23, 2025
  • 0 replies
  • 686 views
Description This article describes how FortiManager analyzes 'Error: -999' to troubleshoot the inability to show the install preview due to invalid CLI syntax.
Scope FortiManager.
Solution

In this scenario, FortiManager Install Preview shows an error message:' Error: -999'.

 

At FortiManager, when the install preview failed, select the 'Log' button to view more information. Select the CLI Template Errors button to know if it is related to a CLI Template error and the error under which line.

 

202509_FMG_InstallCLITemplateError999_001.jpg

 

At FortiGate, verify the CLI syntax is valid inside FortiGate. At FortiManager CLI Template, change the invalid CLI syntax to the valid CLI syntax. After that, FortiManager will be able to show an install preview.

 

202509_FMG_InstallCLITemplateError999_002.jpg

Thought Leadership Security Summit. Outpace New Threats with AI - enhanced defense. Tuesday, Septmeber 15, 8:30 AM - 2:30 PM PT. The Golf Club at Newcastle, WA.
Virtual event | September 2026. SASE summit. The age of autonomous trust. Register here!