Troubleshooting Guide for Error -100120

If you're seeing a score of "-100120" (that's a negative number) for one of your generated schedules, it means that the scheduling engine is working to respect each therapist's maximum group size.

This error is most often caused by having too large of a caseload to fit within your available theraby time.  If you have an unusually large caseload, or relatively few days to see all of your students, the scheduling engine may not have enough available therapy time to squeeze everything in.

If the scheduler completed with this error code (i.e. you see the text "Did not find any solutions" in the Stage column), then this article describes the next steps you should take.  (For background, you may also want to check out Why didn't the engine find any results?.)

If the scheduler is still running (i.e. you see the text "Solving (4 of 6)" in the Stage column), and it's been stuck on this error code for a while (i.e. over an hour), you might want to take corrective action right now. There's a small chance that your caseload will still produce viable schedules before the end of its computation window, but it's not looking good. This article describes the next steps you should take.

The Easy Button

If you're in a rush and prefer not to get into the weeds, try using the following links on your caseload page:

  • Increase maximum group size  (by far, using this caseload transformation is the easiest way to get past this error)
  • Increase maximum grade span
  • Clear delivery models
  • Remove exact time spans
  • Reduce "Days Apart"
  • Unlock therapists
  • Remove therapist "Must Not" entries
  • Convert student "Must Not" entries
  • Convert "Must" groupings
  • Do all reversible transformations
  • The Nuclear Option

This is the quickest (and least-pain) way to get you a good starting point.

Resolve Conflicting Constraints

If your caseload has any conflicting constraints, those must be resolved before the scheduler will succeed. In other words, the scheduler can only find a solution if the puzzle pieces you give it somehow fit together.  More info.

Generally, conflicting constraints are caused by mistakes while entering the caseload data.  Check back over your caseload configuration, and ensure that there are no conflicting pieces of information.

Here are some common conflicts that you might want to look for in your caseload:

  • Double-check the "Maximum Group Size" value for every therapist in your caseload for any entry mistakes
  • Double-check the "Maximum Grade Span" value for every therapist in your caseload for any entry mistakes
  • Double-check the "Exact Time Spans" for every student session in your caseload for any entry mistakes

If you find any of these conflicts, simply remove the conflict and try scheduling again.  While you're editing your caseload, also look for additional instances of that same conflict.

Reduce "Hard" Constraints

If your caseload has too many "hard" constraints, then it will severely slow down the scheduler. In fact, it may slow down so much that it will take weeks or months for the supercomputers to find a solution.  More info.

If this is happening to you, you may either:

  • Remove the "hard" constraints altogether
  • Replace the "hard" constraints with "soft" constraints.  More info.

Generally speaking, please reconsider any self-imposed constraints. Some of your constraints come from your state's laws, or from policies that your administration has put in place. If any of the constraints you've entered are really your own preferences, try removing them. The scheduler works best when the only hard constraints are the ones that are absolutely necessary.

Here are some suggestions for your caseload:

  • Increase the "Maximum Group Size" value for every therapist in your caseload to the legal maximum for your state
  • Increase the "Maximum Grade Span" value for every therapist in your caseload
  • Consider converting student sessions with an "Individual" delivery model to "Unspecified"
  • Reduce your "Minimum Scheduled Interval" value to 5 (or even 1)
  • Instead of scheduling students for multiple sessions per rotation (i.e. per week), schedule each student for only one session per rotation
  • Remove exact time spans from students in your caseload
  • Don't schedule your sessions in alignment with class periods
  • Reduce the "Days Apart" value for every student in your caseload to 0 or 1
  • Un-check the "Locked to Building" checkboxes for every therapist in your caseload
  • Remove any non-critical "Must Not" entries for every therapist in your caseload
  • Remove any non-critical "Must Not" entries for every student in your caseload, or convert them to "Prefer Not" entries

The easiest way to do some of these things is to use one of the following "Caseload Transformations" on your caseload page:

  • Increase maximum group size  (by far, using this caseload transformation is the easiest way to get past this error)
  • Increase maximum grade span
  • Clear delivery models
  • Remove exact time spans
  • Reduce "Days Apart"
  • Unlock therapists
  • Remove therapist "Must Not" entries
  • Convert student "Must Not" entries
  • Convert "Must" groupings
  • Do all reversible transformations
  • The Nuclear Option

However, you can also make manual changes to your caseload to make the updates yourself.

After removing or replacing some/all of your hard constraints, try scheduling again.

Caseload Is Too Large

If you have an unusually large caseload, or relatively few days to see all of your students, the scheduling engine may not have enough available therapy time to squeeze everything in.

Here are some things you can try:

  • Add another day to your schedule (or increase your available hours)
  • Add another therapist to share your caseload
  • Reduce the number of students in your caseload

If these ideas aren't negotiable, then you may need to have a chat with your district about reducing the constraints or size of your caseload. If the engine can't find a solution, then there's a high likelihood that a solution respecting all constraints doesn't mathematically exist.

Last Resort

More info.

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Historical notes:

  • In previous versions of the scheduler, this was known as error -100005.

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