Windows OS - Desktops Pattern sets a object_id on a Computer CI that does not match the object_id on the VM Instance CIDescriptionIn the Windows OS - Desktops Pattern , we are creating the object_id value by a concatenation of account_id, region and instance_id:on_true = set_attr { "cmdb_ci_computer[*].object_id"concat { "amazon$"get_attr {"awsData[1].account_id"}"$"get_attr {"awsData[1].region"}"$"get_attr {"awsData[1].instance_id"}}}The object_id on the VM instance is only the instance/resource ID.In the 'Windows OS - Servers' pattern we can see we are correctly defining the value of the object_idon_true = set_attr { "cmdb_ci_win_server[*].object_id"get_attr {"awsData[1].instance_id"}}Because we are doing a concatenation the Pre/Post Script 'Create Relation Between Host To VM Instance' fails to find a match with the VM instance and is not able to create relationships.That Pre/Post is relying on matching the object_id values at line 93 of Pattern Pre/Post Script 'Create Relation Between Host To VM Instance'.Steps to Reproduce Run Discovery Schedule that discover Windows desktops (on AWS EC2 instance for example).Review the discovery pattern log - find entry such as below:If AWS, set AWS object_id on host2023-10-20 14:55:19: setAttribute(cmdb_ci_computer[*].object_id,amazon$xxx$eu-west-1$i-xxxxxx)Actual behaviour: Confirm that there is no relationship between the Computer CI and the Virtual Machine Instance CI Expected behaviour: There should be a Relation Between Host To VM Instance.WorkaroundThis problem is currently under review and targeted to be fixed in a future release. Subscribe to this Known Error article to receive notifications when more information will be available. Change the following step Step: "If AWS, set AWS object_id on host" from on_true = set_attr { "cmdb_ci_computer[*].object_id" concat {"amazon$" get_attr {"awsData[1].account_id"} "$" get_attr {"awsData[1].region"} "$" get_attr {"awsData[1].instance_id"} } } to on_true = set_attr { "cmdb_ci_computer[*].object_id" get_attr {"awsData[1].instance_id"} } Note: This is going to be treated as a customisation, and future pattern updates and fixes will be skipped. Remember to revert this pattern to the out of box version once you have upgraded to the fixed version. Subscribe to this KB article to get a notification of which version this is fixed out-of-box in.Related Problem: PRB1710491