SharePoint Workflow Manager service constantly restarting - InvalidCastException
We recently started encountering an issue with the Microsoft Workflow Manager. Every few minutes the Workflow Manager service will crash and restart. We have 3 hosts to manage 2013 workflows in our SharePoint 2016 environment. Workflows in the environment continue to work, but sometimes delayed or unavailable. We went ahead and upgraded to the SharePoint workflow manager that was released this year (2023) as the Microsoft one has been deprecated, still with 3 nodes in the farm. We are still encountering the same issue. All that is recorded in the event viewer is "Failed Service Bus Operation: System.InvalidCastException: Specified cast is not valid." Which is then followed by "Application: Microsoft.Workflow.ServiceHost.exe Framework Version: v4.0.30319 Description: The process was terminated due to an unhandled exception." And after a moment or two, the Workflow Service comes back online. My best guess is that there is an offending workflow that is trying to cast an incompatible value? I can't seem to find it though, and I find it odd that it crashes the workflow service and there is no further information on what workflow or where to look to fix it. Nothing in the SPLogfiles that jumps out either. Here are the screenshots from the Event Viewer:
Blank document in 2013 Workflow
I am able to create a document in a library using a 2013 workflow. All the metadata is created correctly. I have chosen the correct content type but the created document is empty. If I do new in the library the document created is perfect and uses the content type template perfectly. Why is the workflow not picking up the content type template? The site is SharePoint 365.
