Running the Scheduler

Once your people, skills, and projects are defined, you are ready to build a schedule.

Open the Plan tab, review the projects and their requirements, and click Build the schedule. Workable sends the plan data to the Google OR-Tools constraint programming engine and usually returns a result in 5 to 30 seconds, depending on complexity.

Understanding Validation Errors

Before Workable tries to build the schedule, it runs a set of validation checks. If one of those checks fails, the build stops and you see an error that points to the problem.

Pre-Build Validation Errors

“Team Size Min must be greater than 0”

This means the team size is 0 or empty. Set the team size to at least one person. See Defining Projects: Team Size.

“At least one Allowed Duration must be specified”

This means the project has no duration set. Enter a project duration in your chosen planning unit. See Defining Projects: Project Duration.

“All Allowed Durations must be greater than 0”

This means the project duration is 0 or negative. Change it to a positive number.

“Either Pinned People must be greater than 0 OR at least one skill requirement with points > 0 must be specified”

This means the project has neither skill requirements nor pinned people. Add at least one skill requirement or pin at least one person. See Defining Projects: Skill Requirements or Expert Assignments: Pinned Assignments.

“Team maximum is less than required positions”

This means the team size is smaller than the number of people the project explicitly requires. Increase team size so it is at least as large as the total required positions. Required positions are calculated from skill quantities plus required people and required teams, with de-duplication.

“Team minimum exceeds required positions”

This means the team size is larger than the explicit requirements. In that case, the scheduler will add extra people without specific skill requirements just to reach the team size. Lower the team size or add more skill requirements if that is not what you want.

Scheduler Execution Errors

“Missing Skills”

This means you have requested a skill that no active person has. Add that skill to at least one person’s profile, change or remove the requirement, or consider using a consultant if the skill is only needed part-time.

“Impossible Constraints”

This means the plan requires more people than are available. You can fix it by adding more people, reducing team size requirements, adjusting project priorities, or reviewing pinned assignments that are blocking availability.

“Unmet Requirements / Low Priority Project Not Scheduled”

This means a lower-priority project ran out of resources after higher-priority projects were scheduled first. Move the project higher in the list, add more people with the required skills, or reduce the demands on higher-priority projects.

“Infeasible / No Solution Found”

This means the combination of constraints makes a valid schedule impossible. Common causes include conflicting pinned assignments, circular dependencies or timing conflicts, too much required work for the available capacity, or public holiday rules removing too many usable days. Review pinned assignments, check the Resource Allocation heatmap for bottlenecks, simplify the constraints temporarily, extend the plan duration, or disable holiday exclusions while you diagnose the issue.

Troubleshooting Tips

When you hit validation errors, work through the plan in a simple order:

1. Check the error message location.
2. Review project requirements in the Plan tab.
3. Verify people have the right skills.
4. Check for over-pinning.
5. Test with simpler constraints.
6. Use scenarios to experiment safely.

Heads up on counting

In Not Scheduled analysis, people included in both Required people and Required teams are counted once.