What causes "Unknown value: " + value" in microsoft/aspire?

Regenerate the Java code from the current ATs schema so the enum includes the new value.

microsoft/aspire · error · IllegalArgumentException (in generated Java code)

Unknown value: " + value

Error message

Unknown value: " + value

What it means

This is not a .NET runtime exception — it is a generated Java source line emitted by AtsJavaCodeGenerator.GenerateEnumTypes (called from GenerateAspireSdk). Every generated Java enum's fromValue method throws IllegalArgumentException("Unknown value: " + value) at Java runtime when the incoming string does not equal any enum constant's value.

Solutions

Regenerate the Java code from the current ATs schema so the enum includes the new value.
Match the exact enum value string (values are case-sensitive in the generated equals check).
Wrap fromValue calls in try/catch (IllegalArgumentException) with a fallback UNKNOWN handling path.
Upgrade the generated SDK package to the version matching the server's enum set.

Example fix

// before
Mode mode = Mode.fromValue(payload.get("mode"));
// after
Mode mode;
try {
    mode = Mode.fromValue(payload.get("mode"));
} catch (IllegalArgumentException e) {
    mode = Mode.UNKNOWN; // handle value from newer schema
}

Defensive patterns

Strategy: try-catch

Validate before calling

// Java: validate before conversion
Set<String> valid = Arrays.stream(Mode.values()).map(Mode::getValue).collect(Collectors.toSet());
if (!valid.contains(rawValue)) {
    // route to fallback instead of fromValue
}

Type guard

// Java
static boolean isKnownMode(String v) {
    return Arrays.stream(Mode.values()).anyMatch(m -> m.getValue().equals(v));
}

Try / catch

try {
    mode = Mode.fromValue(rawValue);
} catch (IllegalArgumentException e) {
    logger.warn("Unknown enum value: {}", rawValue);
    mode = Mode.UNKNOWN;
}

Prevention

Regenerate Java code whenever the ATs schema adds enum values.
Never build enum value strings by hand; use the enum constants.
Design generated enums with an UNKNOWN constant for forward compatibility.

When it happens

Trigger: Calling the generated static method <EnumName>.fromValue(String) in the produced Java SDK with a string that is not one of the declared enum values — e.g., a newer server enum value consumed by older generated code.

Common situations: Server introduces a new enum literal after Java code was generated; hand-written callers pass misspelled or wrong-cased values; deserializing API responses containing values the generator never saw.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

AI-assisted analysis of microsoft/aspire@25830f84bd (2026-09-16). Data as JSON: /api/errors/3892e92ff58cd904. Report an issue: GitHub.

Appendix: source

Thrown at src/Aspire.Hosting.CodeGeneration.Java/AtsJavaCodeGenerator.cs:695

                var member = members[i];
                var memberName = ToUpperSnakeCase(member);
                var suffix = i < members.Length - 1 ? "," : ";";
                WriteLine($"    {memberName}(\"{member}\"){suffix}");
            }
            WriteLine();
            WriteLine("    private final String value;");
            WriteLine();
            WriteLine($"    {enumName}(String value) {{");
            WriteLine("        this.value = value;");
            WriteLine("    }");
            WriteLine();
            WriteLine("    public String getValue() { return value; }");
            WriteLine();
            WriteLine($"    public static {enumName} fromValue(String value) {{");
            WriteLine($"        for ({enumName} e : values()) {{");
            WriteLine("            if (e.value.equals(value)) return e;");
            WriteLine("        }");
            WriteLine("        throw new IllegalArgumentException(\"Unknown value: \" + value);");
            WriteLine("    }");
            WriteLine("}");
            WriteLine();
        }
    }

    private void GenerateDtoTypes(IReadOnlyList<AtsDtoTypeInfo> dtoTypes)
    {
        if (dtoTypes.Count == 0)
        {
            return;
        }

        WriteLine("// ============================================================================");
        WriteLine("// DTOs");
        WriteLine("// ============================================================================");
        WriteLine();

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