Managed Metadata multi-select values in SharePoint Designer Workflow

Scenario

• You wish to use the values in a multi-select managed metadata field in your SharePoint Designer 2010 or 2013 workflow

Issue

• Sometimes the workflow will fail when too many items are selected
• Ex: the term names plus GUIDs exceed 255 characters in the item / fieldname_0 results
• HTTP 500 Error in Workflow Information screen on 2013 workflows:
• RequestorId: GUID. Details: System.ApplicationException: HTTP 500 {"Transfer-Encoding":["chunked"],"X-SharePointHealthScore":["0"],"SPClientServiceRequestDuration":["30"],"SPRequestGuid":["GUID"],"request-id":["GUID"],"X-FRAME-OPTIONS":["SAMEORIGIN"],"MicrosoftSharePointTeamServices":["15.0.0.4667"],"X-Content-Type-Options":["nosniff"],"X-MS-InvokeApp":["1; RequireReadOnly"],"Cache-Control":["max-age=0, private"],"Date":["Fri, 15 Dec 2017 22:29:51 GMT"],"Server":["Microsoft-IIS\/8.0"],"X-AspNet-Version":["4.0.30319"],"X-Powered-By":["ASP.NET"]} at Microsoft.Activities.Hosting.Runtime.Subroutine.SubroutineChild.Execute(CodeActivityContext context) at System.Activities.CodeActivity.InternalExecute(ActivityInstance instance, ActivityExecutor executor, BookmarkManager bookmarkManager) at System.Activities.Runtime.ActivityExecutor.ExecuteActivityWorkItem.ExecuteBody(ActivityExecutor executor, BookmarkManager bookmarkManager, Location resultLocation)

Resolution

• The list item field with _0 after it does support selections over 255 characters, but many Workflow Actions do not support fields larger than 255 characters.
• You cannot:
• Log to History List
• Set Workflow Variable of any types except "Multiple lines of text"
• "Multiple lines of text" is only available from "Initiation Form" parameters
• You can:
• Email text
• Use "contains" operator in an If statement
• I have not gone further in my testing than the above, so please comment on any other actions you identify as working or not working.