microsoft/aspire · error · InvalidDataException

' ' must contain a JSON object.

Error message

'{CurrentStateProperty}' must contain a JSON object.

What it means

The 'currentState' property of the migration state must be a JSON string that itself parses to a JSON object (state is stored serialized as a string). If the parsed value is null or not an object — or JsonNode.Parse fails to yield an object — InvalidDataException is thrown.

Solutions

1. Repair currentState to be a JSON string containing a valid JSON object (e.g. "{}"), or remove the property if the tooling treats null as no current state.
2. Delete the corrupt migration/state file and re-run so it is regenerated.
3. Restore from backup if the file contained real deployment state you need.

Example fix

// before (state file)
{ "currentState": "" }
// after
{ "currentState": "{\"resources\":{}}" }

// currentState must be a string whose content parses to a JSON object
if (migrationState["currentState"] is JsonValue v &&
    (!v.TryGetValue<string>(out var s) || JsonNode.Parse(s) is not JsonObject))
{
    throw new InvalidDataException("currentState must be a JSON string containing a JSON object.");
}

static bool HasValidCurrentState(JsonObject migrationState) =>
    migrationState["currentState"] is not JsonValue v
    || (v.TryGetValue<string>(out var s) && JsonNode.Parse(s) is JsonObject);

try { await manager.LoadStateAsync(ct); }
catch (InvalidDataException ex) when (ex.Message.Contains("currentState") && ex.Message.Contains("JSON object"))
{
    File.Move(statePath, statePath + ".corrupt", overwrite: true);
}

When it happens

Trigger: Loading a migration state file where currentState is an empty string, or a string that parses to null/array/scalar rather than an object.

Common situations: A write that serialized the current state incorrectly or truncated the embedded JSON string; manual edits that emptied the string; schema drift between Aspire versions.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

• ' ' must be a JSON string.
• ' ' must be a JSON string.
• ' ' must be a JSON object.
• Cannot convert to boolean for key
• Deployment state must contain a JSON object.

AI-assisted analysis of microsoft/aspire@25830f84bd (2026-09-16). Data as JSON: /api/errors/2178d66f63f5a703. Report an issue: GitHub.

Appendix: source

Thrown at src/Aspire.Hosting/Pipelines/Internal/FileDeploymentStateManager.cs:765

    {
        var legacyFallbackDisabled = migrationState[LegacyFallbackDisabledProperty]?.GetValue<bool>() ?? false;
        var legacyStateSnapshot = migrationState[LegacyStateProperty] switch
        {
            null => [],
            JsonObject legacyState => legacyState,
            _ => throw new InvalidDataException($"'{LegacyStateProperty}' must be a JSON object.")
        };
        var claimedSectionNames = migrationState[ClaimedSectionsProperty] switch
        {
            null => [],
            JsonValue claimedSectionsValue => ParseClaimedSectionNames(claimedSectionsValue),
            _ => throw new InvalidDataException($"'{ClaimedSectionsProperty}' must be a JSON string.")
        };
        var currentState = migrationState[CurrentStateProperty] switch
        {
            null => null,
            JsonValue stateValue => JsonNode.Parse(stateValue.GetValue<string>())?.AsObject()
                ?? throw new InvalidDataException($"'{CurrentStateProperty}' must contain a JSON object."),
            _ => throw new InvalidDataException($"'{CurrentStateProperty}' must be a JSON string.")
        };

        return new(legacyFallbackDisabled, legacyStateSnapshot, claimedSectionNames, currentState);
    }

    private static string[] ParseClaimedSectionNames(JsonValue claimedSectionsValue)
    {
        var claimedSectionNames = JsonSerializer.Deserialize<string?[]>(
            claimedSectionsValue.GetValue<string>());
        if (claimedSectionNames is null ||
            claimedSectionNames.Any(string.IsNullOrWhiteSpace))
        {
            throw new InvalidDataException(
                $"'{ClaimedSectionsProperty}' must contain a JSON array of non-empty strings.");
        }

        return [.. claimedSectionNames.Select(static sectionName => sectionName!)];

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