We try to execute the automation of Openshift using the ZTP process. In this process it is RedHat ACM that install the Openshift using Baremetals Custom Resource Definition.When RH ACM try to mount the ISO file on the BMS we have this error:

Image provisioning failed: Deploy step deploy.deploy failed: Redfish
    exception occurred. Error: Redfish set boot device failed for node
    79e7762c-0d9b-47a6-98c8-34ded17096f6. Error: HTTP PATCH
    https://10.0.11.3/redfish/v1/Systems/1/Pending returned code 400.
    Base.1.12.GeneralError: A general error has occurred. See ExtendedInfo for
    more information. Extended information: [{'Message': 'The property
    BootSourceOverrideEnabled is a read only property and cannot be assigned a
    value.', 'MessageId': 'Base.1.12.PropertyNotWritable', 'Resolution': 'Remove
    the property from the request body and resubmit the request if the operation
    failed.', '@odata.type': '#Message.v1_1_2.Message', 'MessageSeverity':
    'Warning', 'MessageArgs': ['BootSourceOverrideEnabled']}].

1.
2.
3.

Openshift version that host RH ACM: 4.10.34
RH ACM Operator: 2.6.4
Openshift version to install on targeted BMS: 4.9.53
Targeted cluster will host Mavenir components and has been tested until now with Openshift 4.9 version