bchavez/Bogus · error · ArgumentException

The collection is empty. There are no items to select.

Error message

The collection is empty. There are no items to select.

What it means

Thrown by Randomizer.CollectionItem<T> when collection.Count <= 0. The method uses Skip(r).First() so it needs at least one element. The param is named 'collection'.

Source

Thrown at Source/Bogus/Randomizer.cs:571

   }

   /// <summary>
   /// Get a random subset of a List.
   /// </summary>
   /// <param name="items">The source of items to pick from.</param>
   /// <param name="count">The number of items to pick; otherwise, a random amount is picked.</param>
   public IList<T> ListItems<T>(List<T> items, int? count = null)
   {
      return ListItems(items as IList<T>, count);
   }

   /// <summary>
   /// Get a random collection item.
   /// </summary>
   public T CollectionItem<T>(ICollection<T> collection)
   {
      if( collection.Count <= 0 )
         throw new ArgumentException("The collection is empty. There are no items to select.", nameof(collection));

      var r = Number(max: collection.Count - 1);
      return collection.Skip(r).First();
   }

   /// <summary>
   /// Replaces symbols with numbers.
   /// IE: ### -> 283
   /// </summary>
   /// <param name="format">The string format</param>
   /// <param name="symbol">The symbol to search for in format that will be replaced with a number</param>
   public string ReplaceNumbers(string format, char symbol = '#')
   {
      return ReplaceSymbols(format, symbol, () => Convert.ToChar('0' + Number(9)));
   }

   /// <summary>
   /// Replaces each character instance in a string.

View on GitHub (pinned to 6ece18c5c2)

Solutions

1. Check collection.Count > 0 before calling CollectionItem.
2. Populate or supply a fallback collection.
3. Guard upstream filters that can yield empty results.

Example fix

// before
var v = f.Random.CollectionItem(set);
// after
var v = set.Count > 0 ? f.Random.CollectionItem(set) : defaultValue;

static T SafeCollectionItem<T>(Bogus.Randomizer r, ICollection<T> c, T fallback) {
    return c.Count > 0 ? r.CollectionItem(c) : fallback;
}

bool HasItems<T>(ICollection<T> c) => c.Count > 0;

try { return r.CollectionItem(c); }
catch (ArgumentException ex) when (ex.Message.Contains("collection is empty")) {
    return default;
}

When it happens

Trigger: Calling f.Random.CollectionItem(new HashSet<T>()) or any ICollection<T> with zero elements.

Common situations: Passing an empty set/dictionary-keys collection; results of a where-filter that produced nothing.

Related errors

• The array is empty. There are no items to select.
• The list is empty. There are no items to select.
• max digit can't be lager than 9 or smaller than 0
• The min/max range is invalid. The minimum value '{min}' is g
• The specified range does not contain any even numbers.

AI-assisted analysis of bchavez/Bogus@6ece18c5c2 (2026-08-13). Data as JSON: /api/errors/226613555a6c4f68. Report an issue: GitHub.