When working in the Workflow Designer, users may encounter the message "Workflow Designer encountered problems with your document" accompanied by the following error code:
'Symbol' property has already been set on 'Sequence'.
So, why does this happen?
This error is casued by a known bug in the .NET 4.5 Framework. The error may appear on the local machine of an individual creating a workflow. It can affect JAMS 6.4.X users with any .NET Framework older than .NET 4.6.
To resolve the error message, install .NET 4.6 or newer on the local machine encountering the error:
Download .NET 4.6 or newer by visiting the Microsoft .Net Downloads Page and selecting the appropriate .NET version, 4.6 or higher. Follow the installation instructions given by Microsoft.