HMCL-dev/HMCL · error · IOException

Malformed modpack configuration:

Error message

Malformed modpack configuration: 

What it means

Thrown during Mcbbs modpack export when the instance's Minecraft version cannot be resolved to a valid GameVersionNumber. The exporter must write a valid gameVersion into the mcbbs manifest, so an unparseable/unknown version is a hard stop (IOException). This typically happens when the instance's version JSON is missing, malformed, or inherits from a broken base.

Solutions

1. Open the instance and verify its game version is set and valid in the instance settings
2. Check the instance's version JSON (versions/<id>/<id>.json) for a valid id and complete inheritance chain
3. Re-download or re-create the instance if its version JSON is corrupted
4. Export a different, healthy instance to confirm the exporter works

Example fix

// broken instance json (no id / bad version)
{"inheritsFrom": "1.7.10-missing"}
// after: point to an existing installed version
{"id": "1.7.10", "inheritsFrom": "1.7.10"}

GameVersionNumber v = instance.getVersion();
if (v == GameVersionNumber.unknown())
    throw new IllegalStateException("Fix instance version before exporting: " + instanceId);

if (instance.getVersion() != GameVersionNumber.unknown()) { /* safe to export */ }

try { task.execute(); } catch (IOException e) { if (e.getMessage().startsWith("Cannot parse the version")) { /* prompt user to fix instance version */ } else throw e; }

When it happens

Trigger: Calling McbbsModpackExportTask.execute() on an instance whose version cannot be parsed by GameVersionNumber — e.g. instance JSON has no/invalid id or inheritsVersion chain is broken, so instance.getVersion() returns GameVersionNumber.unknown().

Common situations: Exporting a corrupted or manually edited instance; exporting an instance created from a damaged version JSON; exporting an instance whose inherited parent version was deleted; exporting vanilla/packaged instances with non-standard version ids.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

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

Related errors

• Cannot parse the version of
• Unsupported icon file:
• Missing hmcl.lwjgl-unsafe-agent.version attribute
• Invalid library path:
• /assets/

AI-assisted analysis of HMCL-dev/HMCL@24702dc5a0 (2026-09-10). Data as JSON: /api/errors/da60eaebae06c35e. Report an issue: GitHub.

Appendix: source

Thrown at HMCL/src/main/java/org/jackhuang/hmcl/game/HMCLGameInstance.java:156

    ///
    /// @return whether [#getModpackConfigurationFile()] exists
    public boolean isModpack() {
        return Files.exists(getModpackConfigurationFile());
    }

    /// Reads this instance's HMCL modpack configuration.
    ///
    /// @return the parsed configuration, or `null` when the file does not exist
    /// @throws IOException if the configuration cannot be read
    public @Nullable ModpackConfiguration<?> readModpackConfiguration() throws IOException {
        Path file = getModpackConfigurationFile();
        if (Files.notExists(file)) {
            return null;
        }
        try {
            return JsonUtils.fromJsonFile(file, ModpackConfiguration.class);
        } catch (JsonParseException e) {
            throw new IOException("Malformed modpack configuration: " + file, e);
        }
    }

    @Override
    public Path getRunDirectory() {
        return getRepository().computeRunDirectory(getId(), isModpack(), getSettings());
    }

    /// Returns the loaded instance-local game settings, loading them while this instance is current.
    ///
    /// @return the settings, or `null` when no local settings exist after loading
    public @Nullable GameSettings.Instance getSettings() {
        ensureGameSettingsLoaded();
        return gameSettings;
    }

    /// Returns the instance-local game settings, creating an empty settings object when absent.
    ///

View on GitHub (pinned to 24702dc5a0)