Technical Tip: Error: 'To successfully upgrade to FortiWLM 8.6.5, you are required to install a patch. Contact Fortinet Customer Support to obtain and install the relevant patch.'

• Restoring a backup file for a FortiWLM after upgrading to version 8.6.5 using an older backup (from versions 8.6.3 or 8.6.4) may fail due to incomplete backup files generated with those earlier versions.
• To resolve this issue, a patch file needs to be installed first on top of version 8.6.3 or 8.6.4 and then proceed with an upgrade to v8.6.5.

Steps to Follow: 

1. Apply the latest 64-bit patch: 

• The patch file to be applied on top of FortiWLM running 8.6.3 (64-bit) is ==> forti-8.6-3build-8-patch-restore_backup_patch_x86_64-generic-rpm.tar.fwlm
• The patch file to be applied on top of FortiWLM running 8.6.3 (32-bit) is ==> forti-8.6-3build-8-patch-backup_restore_patch_i386-generic-rpm.tar.fwlm
• The patch file to be applied on top of FortiWLM running 8.6.4 (64-bit) is ==> forti-8.6-4build-6-patch-restore_backup_patch_x86_64-generic-rpm.tar.fwlm

2. Perform backup
3. Upgrade to FortiWLM 8.6.5.

The patch files are not available in the support portal. Submit a ticket to Fortinet support to request these files before initiating the upgrade to v8.6.5.

Related articles: 
About FortiWLM 8.6.5
Supported FortiWLM Upgrades 

Migrating from FortiWLM 32-bit to FortiWLM 64-bit | FortiWLM 8.6.5 | Fortinet Document Library