HMCL-dev/HMCL · error · JsonParseException

UUID malformed

Error message

UUID malformed

What it means

Identical to the hyphenated UUIDTypeAdapter: this adapter parses a JSON string into a UUID and wraps any IllegalArgumentException from UUIDs.parse in a JsonParseException reading 'UUID malformed'. Despite the class name suggesting unhyphenated input, both adapters go through UUIDs.parse.

Solutions

1. Correct the UUID string in the source JSON to a valid 32-char unhyphenated or 36-char hyphenated form as appropriate.
2. Normalize UUIDs (strip or add dashes) before serialization so the stored format matches the adapter in use.
3. Catch JsonParseException around deserialization and repair or regenerate the identifier.

Example fix

// before
String raw = "e3f1c2a4b5d6478f90a1b2c3d4e5f6a7-"; // trailing junk
UUID id = UnhyphenatedUUIDTypeAdapter.INSTANCE.read(reader);

// after
String raw = rawInput.trim().replace("-", "");
if (raw.length() == 32 && raw.chars().allMatch(c -> Character.isLetterOrDigit(c) && c < 'g')) {
    UUID id = UUIDs.parse(raw);
}

static boolean isUnhyphenatedUuid(String s) { return s != null && s.matches("[0-9a-fA-F]{32}"); }

static @Nullable UUID safeParseCompact(String s) { return s != null && s.matches("[0-9a-fA-F]{32}") ? UUIDs.parse(s) : null; }

try { return UnhyphenatedUUIDTypeAdapter.INSTANCE.read(reader); } catch (JsonParseException e) { log.warn("Malformed compact UUID", e); return null; }

When it happens

Trigger: reader.nextString() yields a string UUIDs.parse cannot decode — wrong length, non-hex characters, or a hyphenated UUID where the compact form is expected (or vice versa).

Common situations: Mojang-style unhyphenated UUID data mixed with hyphenated IDs in stored JSON; truncated or corrupted account/profile files; copy-paste errors in identifiers.

Understand the failure class

Background: "invalid id" errors: invalid identifier format — why libraries reject IDs before lookup, and how to fix them — this error's family across 37 libraries.

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

• UUID malformed
• Config is not an object:
• Expected JsonObject but got
• json.toString()
• PortablePath must be a string: " + in.peek()

AI-assisted analysis of HMCL-dev/HMCL@24702dc5a0 (2026-09-10). Data as JSON: /api/errors/372bc7511989f13e. Report an issue: GitHub.

Appendix: source

Thrown at HMCLCore/src/main/java/org/jackhuang/hmcl/util/gson/UnhyphenatedUUIDTypeAdapter.java:55

    /// Writes a UUID as a lowercase string without hyphens.
    @Override
    public void write(JsonWriter writer, @Nullable UUID value) throws IOException {
        writer.value(value == null ? null : UUIDs.toCompactString(value));
    }

    /// Reads a UUID from a standard or unhyphenated UUID string.
    @Override
    public @Nullable UUID read(JsonReader reader) throws IOException {
        if (reader.peek() == JsonToken.NULL) {
            reader.nextNull();
            return null;
        }

        try {
            return UUIDs.parse(reader.nextString());
        } catch (IllegalArgumentException e) {
            throw new JsonParseException("UUID malformed", e);
        }
    }

    /// Prevents instantiation outside the shared instance.
    private UnhyphenatedUUIDTypeAdapter() {
    }
}

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