JamesNK/Newtonsoft.Json · error · JsonException

Index {0} outside the bounds of JArray.

Error message

Index {0} outside the bounds of JArray.

What it means

Thrown by PathFilter.GetTokenIndex when an array index applied to a JArray is greater than or equal to the array's Count, but only when JsonSelectSettings.ErrorWhenNoMatch is true. Without that flag the filter silently returns null (no match).

Source

Thrown at Src/Newtonsoft.Json/Linq/JsonPath/PathFilter.cs:19

using System.Collections.Generic;
using System.Globalization;
using Newtonsoft.Json.Utilities;

namespace Newtonsoft.Json.Linq.JsonPath
{
    internal abstract class PathFilter
    {
        public abstract IEnumerable<JToken> ExecuteFilter(JToken root, IEnumerable<JToken> current, JsonSelectSettings? settings);

        protected static JToken? GetTokenIndex(JToken t, JsonSelectSettings? settings, int index)
        {
            if (t is JArray a)
            {
                if (a.Count <= index)
                {
                    if (settings?.ErrorWhenNoMatch ?? false)
                    {
                        throw new JsonException("Index {0} outside the bounds of JArray.".FormatWith(CultureInfo.InvariantCulture, index));
                    }

                    return null;
                }

                return a[index];
            }
            else if (t is JConstructor c)
            {
                if (c.Count <= index)
                {
                    if (settings?.ErrorWhenNoMatch ?? false)
                    {
                        throw new JsonException("Index {0} outside the bounds of JConstructor.".FormatWith(CultureInfo.InvariantCulture, index));
                    }

                    return null;
                }

View on GitHub (pinned to 4f73e74372)

Solutions

1. Check the array length before indexing, or omit ErrorWhenNoMatch so out-of-range indices yield no token instead of throwing.
2. Use array slice or scan filters ($..) instead of absolute indices when length is variable.
3. Validate payload shape (e.g. minimum array length) before running the path.

Example fix

// before
token.SelectTokens("$.items[10]", new JsonSelectSettings { ErrorWhenNoMatch = true });
// after
var arr = (JArray)token["items"];
if (arr.Count > 10)
{
    token.SelectTokens("$.items[10]", new JsonSelectSettings { ErrorWhenNoMatch = true });
}

static bool CanIndex(JToken token, int index)
{
    return token is JArray a && index >= 0 && index < a.Count;
}

bool IsIndexableArray(JToken t) => t is JArray && t.HasValues;

try { token.SelectTokens("$.items[10]", settings).ToList(); }
catch (JsonException ex) when (ex.Message.Contains("outside the bounds of JArray"))
{ /* index too large; degrade gracefully */ }

When it happens

Trigger: Calling SelectTokens with ErrorWhenNoMatch=true and an index that exceeds the array size. Example: token.SelectTokens("$.items[10]", new JsonSelectSettings { ErrorWhenNoMatch = true }) on an array with fewer than 11 elements.

Common situations: Hard-coded indices assuming a minimum payload size; payloads that changed shape between environments; negative-or-zero-length arrays from an upstream service outage; enabling ErrorWhenNoMatch to get strict behavior and then hitting variable-length data.

Related errors

• Index {0} outside the bounds of JConstructor.
• Path ended with open query.
• Unknown escape character: \
• Path ended with an open string.
• Path ended with an open regex.

AI-assisted analysis of JamesNK/Newtonsoft.Json@4f73e74372 (2026-08-07). Data as JSON: /api/errors/19c4114288c295e4. Report an issue: GitHub.