Check release notes XMC 8.0.5:
https://documentation.extremenetworks.com/release_notes/NetSight/9035078-09_ExtremeManagementCenter_...
Upgrade Information Extreme Management Center 8.0.5 supports upgrades from Extreme Management Center version 7.1.3 only. If you are upgrading from a NetSight/Extreme Management Center version prior to 7.1.3, you must perform an intermediate upgrade. For example, if you are upgrading from Extreme Management Center 7.0, you must first upgrade to Extreme Management Center 7.1.3, and then upgrade to Extreme Management Center 8.0.5.
IMPORTANT:
When performing an upgrade, be sure to back up the database prior to performing the upgrade, and save it to a safe location. Use the Administration > Backup/Restore tab to perform the backup.
The NetSight Server service may not start after upgrading Extreme Management Center to version 8.0.5 on a system on which the Windows Server 2008 operating system is installed. Restarting Windows corrects this issue.
When upgrading the Application Analytics engines to version 8.0.5 after upgrading from version 6.1 to 7.1.3, the upgrade does not complete successfully. To successfully upgrade the engine to version 8.0.5 after upgrading from version 6.1 to 7.1.3, enter dpkg --purge postgresql* in the command line, then upgrade the Application Analytics engine to version 8.0.5.
Important Upgrade Considerations l
When upgrading the Extreme Management Center server, Application Analytics engine, or Extreme Access Control engine to version 8.0.5,
ensure the DNS server IP address is correctly configured. Additionally, upgrading requires an internet connection and may take additional time due to the upgrade of the Linux Ubuntu operating system from version 12 to version 14. During this time, the engine may not be accessible via SSH. If no internet connection is available, see Migrating or Upgrading to a 64-bit Extreme Management Center Engine.
Volker