microsoft/aspire · error · InvalidOperationException

No log entry found in OTLP data.

Error message

No log entry found in OTLP data.

What it means

GetStructuredLogJson serializes the first log record from OTLP resource-logs data into a JSON string (for AI/dashboard consumption). It throws InvalidOperationException when the OTLP payload contains no log records at all, i.e. GetLogRecordsFromOtlpData returns an empty sequence, so FirstOrDefault has nothing to return.

Solutions

1. Check that resourceLogs is non-null and contains at least one log record before calling GetStructuredLogJson
2. Inspect GetLogRecordsFromOtlpData output to confirm the OTLP payload actually decoded records (scopeLogs, logRecords arrays present)
3. Guard the call site: only invoke when a prior query returned a non-empty record count
4. If an empty result is legitimate for your flow, handle the empty case yourself instead of forcing the throw

Example fix

// before
var json = SharedAIHelpers.GetStructuredLogJson(resourceLogs, getResourceName);
// after
var hasRecords = SharedAIHelpers.GetLogRecordsFromOtlpData(resourceLogs).Any();
var json = hasRecords
    ? SharedAIHelpers.GetStructuredLogJson(resourceLogs, getResourceName)
    : null; // handle empty OTLP data explicitly

var records = SharedAIHelpers.GetLogRecordsFromOtlpData(resourceLogs);
if (!records.Any()) return null; // skip serialization for empty OTLP data

try { return SharedAIHelpers.GetStructuredLogJson(resourceLogs, getResourceName); }
catch (InvalidOperationException) { return null; /* empty OTLP payload */ }

When it happens

Trigger: Calling GetStructuredLogJson with an empty or null resourceLogs list, resource logs that contain no scope logs/records, or OTLP JSON that fails to map into any OtlpLogRecord.

Common situations: Passing an empty batch of logs fetched from the OTLP endpoint to an AI assistant prompt; a resource emitted resourceLogs wrapper entries with no actual records; upstream filters removed all records before the call.

Understand the failure class

Background: EmptyResultError / "no results found": when an API or scraper succeeds but returns zero rows — this error's family across 9 libraries.

Related errors

• No trace found in OTLP data.
• Cancellation token must be cancellable in order to prevent…
• Circular loop detected for span
• Dimension limit of reached.
• Duplicate span id ' ' detected.

AI-assisted analysis of microsoft/aspire@25830f84bd (2026-09-16). Data as JSON: /api/errors/eb88a4418207d7a0. Report an issue: GitHub.

Appendix: source

Thrown at src/Shared/ConsoleLogs/SharedAIHelpers.cs:93

        var logsData = jsonArray.ToJsonString(s_jsonSerializerOptions);

        return (logsData, limitMessage);
    }

    /// <summary>
    /// Converts OTLP resource logs to a single structured log JSON for AI processing.
    /// </summary>
    /// <param name="resourceLogs">The OTLP resource logs containing log records.</param>
    /// <param name="getResourceName">Optional function to resolve resource names.</param>
    /// <param name="dashboardBaseUrl">Optional dashboard URL.</param>
    /// <returns>The JSON string for the first log entry.</returns>
    public static string GetStructuredLogJson(
        IList<OtlpResourceLogsJson>? resourceLogs,
        Func<IOtlpResource, string> getResourceName,
        string? dashboardBaseUrl = null)
    {
        var logRecords = GetLogRecordsFromOtlpData(resourceLogs);
        var logEntry = logRecords.FirstOrDefault() ?? throw new InvalidOperationException("No log entry found in OTLP data.");
        var promptContext = new PromptContext();
        var dto = GetLogEntryDto(logEntry, promptContext, getResourceName, dashboardBaseUrl);

        return dto.ToJsonString(s_jsonSerializerOptions);
    }

    /// <summary>
    /// Converts OTLP resource spans to traces JSON for AI processing.
    /// </summary>
    /// <param name="resourceSpans">The OTLP resource spans containing trace data.</param>
    /// <param name="getResourceName">Optional function to resolve resource names.</param>
    /// <param name="dashboardBaseUrl">Optional dashboard URL.</param>
    /// <returns>A tuple containing the JSON string and a limit message.</returns>
    public static (string json, string limitMessage) GetTracesJson(
        IList<OtlpResourceSpansJson>? resourceSpans,
        Func<IOtlpResource, string> getResourceName,
        string? dashboardBaseUrl = null)
    {

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