Description of Problem

• ArgoCD's web console can fail to display an Application if there's a discrepancy in the managing ApplicationSet and the actual applicationset-controller. The issue occurs when the AppSet is configured such that spec.strategy.type: RollingSync, but the applicationset-controller does not have the flags set to enable progressive sync, e.g. --enable-progressive-syncs.

Additional Info

• The issue explicitly requires that the AppSet have the configuration but not the controller, and only occurs in 1.18.0: versions <= 1.17.x are not affected. The issue appears as a stacktrace in UI, and is tracked upstream as well: https://github.com/argoproj/argo-cd/issues/24296

Problem Reproduction

• Issue occurs in any GitOps 1.18.0 install that uses the faulty settings

Reproducibility

• Always

Prerequisites/Environment

• OpenShift 4.19.0 (but presumably any 4.x version)
• OpenShift GitOps 1.18.0

Steps to Reproduce

• Create an OpenShift 4.19.0 cluster
• Install GitOps 1.18.0
• Create an AppSet with spec.strategy.type: RollingSync
• Go to the ArgoCD UI, and click an Application managed by the AppSet
• Witness the UI fill with the stacktrace error, though it doesn't actually crash

Expected Results

• UI displays the Application, even if it is incorrectly configured to use the progressive sync feature

Actual Results

• Displays a stacktrace error

Workaround (If Possible)

• No known workarounds minus outright removing the invalid spec.strategy.type: RollingSync field or explicitly setting the AppSet to use AllAtOnce instead.