Troubleshooting Tip: 'Failed to retrieve preview result' error when running Install Preview in FortiManager

Description

This article describes how to resolve the 'Failed to retrieve preview result' error in Install Preview on FortiManager.

Scope

 FortiManager.

Solution

When installing the policy package into the FortiGate, the install preview may show the following error: 'Failed to retrieve preview result'.

Root cause:

This issue is typically related to internal database inconsistency in FortiManager, including:

• ADOM integrity issues.

• Policy package database inconsistency.

• Configuration database (CDB) corruption or mismatch.

These inconsistencies may prevent FortiManager from correctly generating the preview result.

Solution:

Run the following integrity check commands on the FortiManager CLI:

diagnose pm2 check-integrity all
diagnose dvm check-integrity
diagnose cdb check adom-integrity
diagnose cdb check policy-packages
diagnose cdb upgrade check +all

After executing the commands above, a File system repair of FortiManager is required for the changes to take effect.

Troubleshooting:

Use the following command for a File system repair, which will repair any issues in the file system of the FortiManager and then reboot the instance.

diagnose system fsck harddisk

Additional scenario: Preview shows abnormal content (e.g., 'DV' characters).

Solution:

Make a minor configuration change to trigger a refresh. For example:

• Edit the interface comment field.

• Save the configuration.

The Install Preview will display correctly.