https://community.appian.com/discussions/f/process/37901/at-least-one-referenced-activity-class-schema-is-invalid-282-from-process-prepareexecutionprocessmodelids-on-execution04Hi there, We&#39;re having issues with four process models in one of our lower environments. Three are started from a process start form, and one is just a subprocess in another process model. The error must be occurring before the process actually startsen-USTelligent Community 12https://community.appian.com/thread/142538?ContentTypeID=1Thu, 07 Nov 2024 07:44:52 GMTd3a83456-d57b-489c-a84c-4e8267bb592a:fb075a6a-c7bc-491e-a733-47075f92897bStefan Helzle<p>I just wanted to suggest opening a support case ... which you already did. I still think this is your best bet.</p><div style="clear:both;"></div>