After Workflow Server install SymWebInclude and SymWorkflowPages are configured to work in ProcessManagerPool without that pool existing.
This affects components on form that use scripts from these, for example date picker dropdown.
Workflow installer will set SymWebInclude and SymWorkflowPages to work in ProcessManagerPool without actually creating the pool or checking if that pool exists. That application pool is created by installer as part of Process Manager role installation but installing Process Manager role is not a requirement.
Symantec Engineering is working on the issue.
Create an Application Pool called ProcessManagerPool with suitable configuration (.NET Framework version: v2.0 and Managed Pipeline Mode: Classic).