There are rules on the task form that gets triggered when users attempt to action a task. But these rules will not get executed when users action the task from the worklist control, instead of opening the task form and action the task with the form. How do you prevent this from happening?
In this case, the solution is to hide the task actions on the worklist control to force users to action the task with the task form.
Please note that the changes made will only apply to new instances of the workflow. If there are process instances that are already running before you deploy a new version of the workflow, tasks assigned by those process instances will still have the actions available for selection on the worklist control.
If users are using K2 Workspace to open their tasks, there is a way to hide the task actions on K2 Workspace without making any changes to the workflows.
Go to K2 Management > Users > Workspace Settings, and uncheck Actions.