Matching Failures

Troubleshooting guide

This guide helps you resolve common issues when Derby cannot generate a complete match schedule.

Why Are Some Teams Not Being Matched?

The matching algorithm pairs cards based on weight within a tolerance window. If teams aren't being matched, it's usually due to one of these reasons:

1. Weight Tolerance Too Tight

If your weight tolerance is too small relative to your weight range, some cards may have no valid opponents.

Rule of Thumb

Weight range should be no more than 2× the tolerance. For example, with 60g tolerance, keep your weight range within ~120g (e.g., 2000-2120g).

Solution:

  1. Go to Tournament > Settings
  2. Increase the Weight Tolerance (try 60-80g)
  3. Regenerate the schedule

2. Isolated Cards (Outliers)

If a card's weight is far from others, it may have no valid opponents within tolerance.

How to identify:

  • Derby shows a warning icon next to cards with zero pairing options
  • Check the Teams tab for cards marked as "optionless"

Solutions:

  • Exclude the isolated card using Omit
  • Mark it as a Wildcard (reserve entry)
  • Increase tolerance to include it

3. Odd Number of Cards

If you have an odd number of active cards, one card cannot be paired.

Solutions:

  • Add one more card to make it even
  • Exclude (omit) one card
  • The algorithm will show which card has a "bye"

4. Same-Owner Constraint

Cards from teams owned by the same player cannot fight each other. If a player owns multiple teams, this reduces pairing options.

Solution: Ensure players don't own too many teams relative to the total teams in the tournament.

Schedule Quality Issues

High Weight Differences

If generated schedules have high average weight differences:

  • Try regenerating multiple times (click Generate again)
  • Select a different schedule from the generated options
  • Check that your cards' weights are properly distributed

Teams Fighting Twice

If Unique Matchups is enabled but teams are still fighting twice:

  • You may have too few teams for the number of rounds
  • Try reducing the number of rounds
  • Add more teams to the tournament

Error Messages

Error Cause Solution
"No valid schedule found" Constraints too tight Increase tolerance, reduce rounds, or add teams
"Card has no options" Weight too far from others Omit the card or increase tolerance
"Odd number of entries" Cannot pair all cards Add or remove one card

Still Having Issues?

If you continue to experience matching problems:

  1. Check the FAQ for additional answers
  2. Contact support with your tournament file