Note: Doc team updates the current version of the documentation and the
two previous versions (n-2), but we address *only high-priority, or
customer-reported issues* for -2 releases in support.
Describe the changes in the doc and link to your dev story:

1. - [x] Mandatory: Add the required version to the Fix version/s field.

2. - [ ] Mandatory: Choose the type of documentation change or review.

• [ ] We need to update to an existing topic

• [ ] We need to add a new document to an existing section

• [ ] We need a whole new section; this is a function not
  documented before and doesn't belong in any current section

• [ ] We need an Operator Advisory review and approval

• [x] We need a z-Stream (Errata) Advisory and Release note for
  MCE and/or ACM

3. - [ ] Mandatory: Find the link to where the documentation update
should go and add it to the recommended changes. You can either use the
published doc or the staged repo for this step:

Maybe here ? Or maybe some KCS. Not sure if this below is enough visibility given this error means we cannot recommend customers upgrade to OCP 4.18 at the moment. It is also currently unlcear when the fix for this will be released.

https://docs.redhat.com/en/documentation/red_hat_advanced_cluster_management_for_kubernetes/2.13/html/release_notes/acm-release-notes#known-issues-acm 

4. - [ ] Mandatory for GA content:

• [x] Add steps, the diff, known issue, and/or other important
  conceptual information in the following space:

Upgrading ACM on OCP 4.18 fails with Error installing CRDs
When upgrading ACM on OCP 4.18 upgrades will fail with the following error, which might cause the ACM hub to go into a bad state.

# oc get multiclusterhubs -n open-cluster-management -o yaml
.....
conditions:
    - lastTransitionTime: "2025-03-20T11:58:32Z"
      lastUpdateTime: "2025-03-20T11:58:32Z"
      message: 'Error installing CRDs: CustomResourceDefinition.apiextensions.k8s.io
        "multiclusterobservabilities.observability.open-cluster-management.io" is
        invalid: spec.conversion.webhookClientConfig.caBundle: Invalid value: []byte{0x5c,
        0x6e}: unable to load root certificates: unable to parse bytes as PEM block'
      reason: FailedDeployingComponent
      status: "False"
      type: Progressing
    desiredVersion: 2.13.0
    phase: Installing
....

Workaround:
For installations without Observability enabled the following workaround can be used:

oc delete crd multiclusterobservabilities.observability.open-cluster-management.io

WARNING: If Observability is installed on the cluster this command causes the Observability stack to be deleted. No known workaround exists for setups with Observability enabled.

• [x] *Add Required access level *(example, *Cluster
  Administrator*) for the user to complete the task:
  Cluster admin

• [x] Add verification at the end of the task, how does the user
  verify success (a command to run or a result to see?)

If the workaround is applied, progress of the ACM upgrade can be followed with the below command. The output should note that all hub components are ready:

 # oc get multiclusterhubs -n open-cluster-management -o yaml
.....
conditions:
    - lastTransitionTime: "2025-03-20T16:48:48Z"
      lastUpdateTime: "2025-03-20T16:48:48Z"
      message: 'created new resource: CustomResourceDefinition multiclusterobservabilities.observability.open-cluster-management.io'
      reason: NewResourceCreated
      status: "True"
      type: Progressing
    - lastTransitionTime: "2025-03-20T16:53:34Z"
      lastUpdateTime: "2025-03-20T16:53:34Z"
      message: All hub components ready.
      reason: ComponentsAvailable
      status: "True"
      type: Complete

• [x] Add link to dev story here: Fixing the bug happens here https://issues.redhat.com/browse/ACM-19094

5. - [ ] Mandatory for bugs: What is the diff? Clearly define what the
problem is, what the change is, and link to the current documentation. Only
use this for a documentation bug.