If you are facing error like "Target date not found in work calendar error" during workflow configuration or process then you can do following things
This problem occured because calendar not set for workflow you can set it by going following menu
Basic->common form ->Go to calendar
Enter calendar details if its missing and make control field open if its closed then go to workflow configuration select this calendar.
If you done correctly then this error will resolved automatically so do not worry its not technical error its functional issue.