The following ACNS software release upgrades can be performed:
Any ACNS 5.1.x, ACNS 5.2.x, ACNS 5.3.x release to any ACNS 5.4.x release.
Any ACNS 4.2.x release (except ACNS 4.2.1) to any ACNS 5.x.x release (except ACNS 5.4.x).
Any ACNS 5.x.x release to any ACNS 5.x.x release, with the following exception:
Direct upgrade from ACNS 5.0.x to ACNS 5.4.x is not allowed.
From ACNS 5.0.x software, first upgrade to ACNS 5.1.x, ACNS 5.2.x, or ACNS 5.3.x before you upgrade to ACNS 5.4.x.