OrchardCMS/OrchardCore · error · ArgumentException

Invalid prefix query

Error message

Invalid prefix query

What it means

This is PrefixFilterProvider.CreateFilteredQuery's default switch branch. The prefix filter's value was neither an object (with a "prefix" property) nor the other handled value kind, so no PrefixQuery could be built and the provider throws ArgumentException("Invalid prefix query").

Solutions

1. Wrap the prefix in an object: {"prefix": {"Title": {"prefix": "Orch"}}}.
2. Ensure the value's JSON kind is one the provider handles (object with "prefix", or string) before calling CreateFilteredQuery.
3. Search saved queries/recipes for prefix filters with non-object values and fix them.
4. Log the raw filter JSON in a try/catch around CreateFilteredQuery to find the malformed node.

Example fix

// before
{"prefix": {"Title": 123}}
// after
{"prefix": {"Title": {"prefix": "123"}}}

if (filter.TryGetPropertyValue(field, out var v) &&
    v.ValueKind is not (JsonValueKind.String or JsonValueKind.Object))
{
    throw new InvalidOperationException(
        $"prefix value for '{field}' must be a string or object, got {v.ValueKind}.");
}

static bool IsValidPrefixValue(JsonElement v) =>
    v.ValueKind is JsonValueKind.String or JsonValueKind.Object;

try
{
    var query = provider.CreateFilteredQuery(context);
}
catch (ArgumentException ex) when (ex.Message.Contains("Invalid prefix"))
{
    _logger.LogError(ex, "Unsupported prefix value kind: {Json}", filterJson);
    throw new QueryValidationException("prefix filters require string or object values.", ex);
}

When it happens

Trigger: Passing {"prefix": {"Title": 123}} or {"prefix": {"Title": true}} or {"prefix": {"Title": null}} — a scalar/null value where an object (or the accepted simple form) is expected, causing the value-kind switch to fall to default.

Common situations: Query JSON generated by code that serializes numbers/booleans as-is; copying a wildcard-style filter definition into a prefix filter; a saved query written against an older syntax that no longer parses in the current Orchard Core version.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

• Invalid query
• Invalid wildcard query
• Missing value in match phrase query
• Prefix query misses prefix value
• Invalid range query

AI-assisted analysis of OrchardCMS/OrchardCore@4306c0717f (2026-09-13). Data as JSON: /api/errors/74963c1213abb67a. Report an issue: GitHub.

Appendix: source

Thrown at src/OrchardCore/OrchardCore.Lucene.Core/QueryProviders/Filters/PrefixFilterProvider.cs:55

                {
                    prefixQuery = new PrefixQuery(new Term(first.Key, value.Value<string>()));
                }
                else if (obj.TryGetPropertyValue("prefix", out var prefix))
                {
                    prefixQuery = new PrefixQuery(new Term(first.Key, prefix.Value<string>()));
                }
                else
                {
                    throw new ArgumentException("Prefix query misses prefix value");
                }

                if (obj.TryGetPropertyValue("boost", out var boost))
                {
                    prefixQuery.Boost = boost.Value<float>();
                }

                break;
            default: throw new ArgumentException("Invalid prefix query");
        }

        booleanQuery.Add(prefixQuery, Occur.MUST);
        var queryFilter = new QueryWrapperFilter(prefixQuery);

        return new FilteredQuery(booleanQuery, queryFilter);
    }
}

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