Issue
When publishing a workflow, the following error might occur:
Error publishing workflow. Workflow XAML failed validation due to the following errors: Activity 'FormatString' has XX arguments, which exceeds the maximum number of arguments per activity (50). Activity `FormatString` has 59 arguments, which exceeds the maximum number of arguments per activity (50). (...). The remote server returned an error: (400) Bad Request.
Error publishing workflow. Workflow XAML failed validation due to the following errors: Activity 'FormatString' has XX arguments, which exceeds the maximum number of arguments per activity (50). Activity `FormatString` has 59 arguments, which exceeds the maximum number of arguments per activity (50). (...). The remote server returned an error: (400) Bad Request.
Resolution
Reduce the number of field entries to be render into and the error should disappear and the publish should work.
Additional Information
SharePoint Workflow Manager has a limitation of 50 references for a 'FormatString' Activity. This can surface either in Log to History Actions (if the character limitation is not reached first) or by trying to render those in an action such as a "Send Email" or "Assign Task".