OrchardCMS/OrchardCore · error · FormatException

Unsupported JSON token

Error message

Unsupported JSON token '{value.ValueKind}' was found.

What it means

VisitValue handles Object, Array, Number, String, True, False and Null JSON value kinds; any other ValueKind reaching the default branch throws FormatException 'Unsupported JSON token ... was found.'. In practice this is a defensive invariant for JsonValueKind values not covered (e.g. Undefined from a default-constructed element).

Solutions

1. Inspect the ValueKind reported in the message and ensure only well-formed JsonDocument/JsonElement values are traversed
2. Upgrade or check OrchardCore/System.Text.Json version alignment if a new JsonValueKind appeared
3. Avoid constructing JsonElement manually; always parse via JsonDocument.Parse
4. Capture the full exception with a stack trace to identify which property produced the unsupported token

// Ensure elements come from a parsed document
using var doc = JsonDocument.Parse(document, JOptions.Document); // ValueKinds are then always one of the supported kinds

try { JsonConfigurationParser.Parse(document); }
catch (FormatException ex) when (ex.Message.StartsWith("Unsupported JSON token"))
{ log.LogError(ex, "Uninitialized/unsupported JsonElement encountered"); }

When it happens

Trigger: Extremely rare with normal System.Text.Json parsing; occurs if a default(JsonElement) or otherwise uninitialized element (ValueKind Undefined/Uninitialized) is passed into the visitor, typically through reflection, custom subclassing, or a bug in calling code constructing elements manually.

Common situations: Custom code paths or tests that hand-construct JsonElement values; a framework/version change introducing a new ValueKind not yet handled by this parser; debugging tools feeding synthetic elements.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

• A duplicate key ' ' was found.
• Can't use the non numeric key
• Can't use the numeric key
• is missing the required "orchardBaseUrl" field.
• Could not parse the JSON document.

AI-assisted analysis of OrchardCMS/OrchardCore@4306c0717f (2026-09-13). Data as JSON: /api/errors/bdab7149303adb6c. Report an issue: GitHub.

Appendix: source

Thrown at src/OrchardCore/OrchardCore.Abstractions/Shell/Configuration/Internal/JsonConfigurationParser.cs:166

            case JsonValueKind.Null:

                // Skipping null values is useful to override array items,
                // it allows to keep non null items at the right position.
                if (visitArray && value.ValueKind == JsonValueKind.Null)
                {
                    break;
                }

                var key = _paths.Peek();
                if (_data.ContainsKey(key))
                {
                    throw new FormatException($"A duplicate key '{key}' was found.");
                }
                _data[key] = value.ToString();
                break;

            default:
                throw new FormatException($"Unsupported JSON token '{value.ValueKind}' was found.");
        }
    }

    private void EnterContext(string context) =>
        _paths.Push(_paths.Count > 0 ?
            _paths.Peek() + ConfigurationPath.KeyDelimiter + context :
            context);

    private void ExitContext() => _paths.Pop();
}

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