By Tiaan Rossouw, Office 365 Practice Lead for Intervate
After a recent .NET Framework security update is run on servers, SharePoint on premise workflows have stopped running.
The security update is the .NET Framework September 2018 Security and Quality Rollup. It is designed to fix the identified CVE-218-8421 .NET vulnerability, but this has the side-effect of also not allowing SharePoint workflows to talk to .NET on the servers.
To check if this is happening in your environment, open the workflow details for a list or document item where a workflow was started on. If you see the following, you have a problem:
The good news is that it is easily fixed with a minor change to your web.config file for all web applications on all your SharePoint servers in the farm. Please contact Intervate on firstname.lastname@example.org for assistance on this issue.