The EAP XP installation guide [1] mentions that having installation-manager is one of the pre-requisites, however it does not mention that the installation-manager needs to be from Update 02 or newer.

The correct installation-manager can be downloaded from the EAP 8.0 patches page [2] or it can be self-updated from the GA version using ./bin/jboss-eap-installation-manager.sh update perform --self

To confirm the correct versions, users can run ./bin/jboss-eap-installation-manager.sh --version and make sure the version is 1.1.11.Final-redhat-00003 or newer.

Note, this applies to XP 5.0 documentation, for XP 6.0 it might not be relevant.

[1] https://docs.redhat.com/en/documentation/red_hat_jboss_enterprise_application_platform/8.0/html-single/using_jboss_eap_xp_5.0/index
[2] https://access.redhat.com/jbossnetwork/restricted/listSoftware.html?product=appplatform&downloadType=patches&version=8.0