microsoft/aspire · error · JsonException

Expected a non-empty Kubernetes MicroTime value.

Error message

Expected a non-empty Kubernetes MicroTime value.

What it means

Thrown by KubernetesMicroTimeJsonConverter.Read when the JSON value is a string but empty (or null-string). Kubernetes MicroTime values must be a non-empty RFC3339 timestamp; the converter rejects empty strings before attempting ParseExact.

Solutions

1. Emit null instead of "" when the timestamp is absent.
2. Populate the field with a valid RFC3339 UTC string such as "2024-01-01T00:00:00Z".
3. Sanitize incoming payloads: replace empty strings with null before deserialization if the source cannot be fixed.

Example fix

// before
{ "lastUpdate": "" }
// after
{ "lastUpdate": null }

if (payload.LastUpdate is "") payload.LastUpdate = null; // normalize empty to null before deserializing

static bool IsValidMicroTime(string? s) => !string.IsNullOrEmpty(s) && DateTimeOffset.TryParse(s, CultureInfo.InvariantCulture, DateTimeStyles.AssumeUniversal, out _);

try { time = JsonSerializer.Deserialize<KubernetesMicroTime>(ref reader, options); }
catch (JsonException ex) when (ex.Message.Contains("non-empty")) { time = null; /* treat as missing */ }

When it happens

Trigger: Deserializing JSON where a MicroTime field is "" (empty string). Note a literal JSON null is tolerated earlier and yields null, so this only fires for empty/whitespace strings.

Common situations: Server or mock omitting the timestamp but serializing an empty string instead of null; placeholder fixtures with blank timestamps; partially initialized DCP state.

Understand the failure class

Background: "must not be empty", "cannot be empty" — required-field validation errors across open-source libraries — this error's family across 41 libraries.

Related errors

• Expected a string token for Kubernetes MicroTime but found
• Cannot convert string
• Error deserializing GenAI message content. Error description
• Expected PropertyName, got
• Expected StartObject, got

AI-assisted analysis of microsoft/aspire@25830f84bd (2026-09-16). Data as JSON: /api/errors/068d0681534a5e69. Report an issue: GitHub.

Appendix: source

Thrown at src/Aspire.Hosting/Dcp/Model/KubernetesMicroTimeJsonConverter.cs:30

    private const string UtcFormat = "yyyy-MM-dd'T'HH:mm:ss.ffffff'Z'";
    private const string OffsetFormat = "yyyy-MM-dd'T'HH:mm:ss.ffffffzzz";

    public override DateTime? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
    {
        if (reader.TokenType is JsonTokenType.Null)
        {
            return null;
        }

        if (reader.TokenType is not JsonTokenType.String)
        {
            throw new JsonException($"Expected a string token for Kubernetes MicroTime but found {reader.TokenType}.");
        }

        var value = reader.GetString();
        if (string.IsNullOrEmpty(value))
        {
            throw new JsonException("Expected a non-empty Kubernetes MicroTime value.");
        }

        return value.EndsWith('Z')
            ? DateTime.ParseExact(value, UtcFormat, CultureInfo.InvariantCulture, DateTimeStyles.AssumeUniversal | DateTimeStyles.AdjustToUniversal)
            : DateTimeOffset.ParseExact(value, OffsetFormat, CultureInfo.InvariantCulture, DateTimeStyles.AssumeUniversal | DateTimeStyles.AdjustToUniversal).UtcDateTime;
    }

    public override void Write(Utf8JsonWriter writer, DateTime? value, JsonSerializerOptions options)
    {
        if (value is null)
        {
            writer.WriteNullValue();
            return;
        }

        // DCP models these fields as Kubernetes metav1.MicroTime, whose JSON shape is fixed-width:
        //   "2026-07-15T18:46:06.123000Z"
        // See https://github.com/kubernetes/apimachinery/blob/v0.36.0/pkg/apis/meta/v1/micro_time.go.

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