If a VMware ESX/ESXi version does not have upgrade support, perform a clean installation, after you save your VMFS datastore to another location or partition.

You can upgrade most versions of VMware ESX/ESXi to the ESX 4.0/ESXi 4.0 version. You cannot perform an in-place upgrade from ESX to ESXi (or from ESXi to ESX). To upgrade virtual machines from ESX to ESXi (or from ESXi to ESX), you must perform a migration upgrade.

Upgrade Support for ESX/ESXi gives details of upgrade support for ESX and ESXi. Upgrade support for a version of ESX/ESXi includes all associated update releases. For example, where upgrading from ESX 3.5 is supported, upgrades from ESX 3.5 Update 1, ESX 3.5 Update 2, and so on are included.

Upgrade Support for ESX/ESXi

ESX Version

Support

ESX alpha, beta, or RC release (any)

No upgrade support

ESX 1.x

No upgrade support

ESX 2

No upgrade support

ESX 2.1

No upgrade support

ESX 2.1.1

No upgrade support

ESX 2.1.2

No upgrade support

ESX 2.1.3

No upgrade support

ESX 2.5

No upgrade support

ESX 2.5.1

No upgrade support

ESX 2.5.2

No upgrade support

ESX 2.5.3

No upgrade support

ESX 2.5.4

No upgrade support

ESX 2.5.5

Limited support

ESX 3.0.0

Limited support

ESX 3.0.1

Limited support

ESX 3.0.2

Yes

ESX 3.0.3

Yes

ESX 3.5

Yes

ESXi 3.5

Yes

ESX 4.0

Yes

ESXi 4.0

Yes