Hi Nor Salwa Abd Wahab,
Thank you for posting your question in the Microsoft Q&A forum.
Based on your description, it sounds like you're experiencing a workflow issue in SharePoint 2019 where the "Approval failed to start" error has only recently appeared. You suspect it might be related to a recent security update, but you're not certain yet.
To better understand your situation, could you please share:
- Which KB update was recently installed?
- What changes or components were included in that update?
In the meantime, I’ve looked into this and found that you can check the ULS logs on your SharePoint server to trace any workflow-related anomalies. Microsoft has a helpful article on how to do this here: View diagnostic logs in SharePoint
Also, based on your screenshot and the error message, I found a couple of related threads that might help you troubleshoot further:
I hope the information above help! Let me know if you can share more details about your environment or recent updates.
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