Pumpkin-MC/Pumpkin · error · ManagerError

Loader error

Error message

Loader error: {0}

What it means

ManagerError::LoaderError(#[from] LoaderError) wraps a lower-level plugin LoaderError inside the plugin manager's error enum, displayed as "Loader error: {0}". It surfaces when a load/unload operation fails inside the plugin loader itself (e.g. jar reading, WASM instantiation, manifest parsing) rather than in manager bookkeeping. Use its source to see the underlying loader failure.

Solutions

  1. Read the wrapped LoaderError message for the concrete cause (IO, instantiation, or metadata failure)
  2. Rebuild/re-download the plugin for the running server's plugin API version
  3. Validate the plugin file (correct jar/wasm, intact manifest) before loading
  4. Test the plugin standalone or update the server if the plugin requires a newer loader
Defensive patterns

Strategy: try-catch

Validate before calling

// verify plugin file before load attempt
let path = Path::new(&plugin_path);
if !path.is_file() || MetadataExt::size(&path.metadata()?) == 0 {
    return Err("plugin file missing or empty".into());
}

Try / catch

match manager.load_plugin(path) {
    Err(ManagerError::LoaderError(e)) => {
        error!("loader failure for {path}: {e}");
        // inspect e (and its source chain) for the concrete cause
    }
    other => other?,
}

Prevention

When it happens

Trigger: Loading a plugin whose file is corrupt, whose WASM module fails to instantiate, or whose plugin metadata/manifest is invalid; the manager propagates the loader's error via the #[from] conversion.

Common situations: Dropping an incompatible or corrupted plugin file into the plugins folder; plugin compiled against a different plugin API/WIT version than the server supports; malformed plugin metadata in the jar.

Related errors

AI-assisted analysis of Pumpkin-MC/Pumpkin@8d4639e25a (2026-09-09). Data as JSON: /api/errors/304a915cb7925833. Report an issue: GitHub.

Appendix: source

Thrown at crates/pumpkin/src/plugin/mod.rs:221

///
/// OS specific issues
/// - Windows: Plugin cannot be unloaded, it can be only active or not
struct LoadedPlugin {
    metadata: PluginMetadata,
    instance: Option<Arc<dyn Plugin>>,
    loader: Arc<dyn PluginLoader>,
    loader_data: Option<Box<dyn Any + Send + Sync>>,
    is_active: bool,
    context: Arc<Context>,
    path: PathBuf,
}

/// Error types for plugin management
#[derive(Error, Debug)]
pub enum ManagerError {
    #[error("Plugin not found: {0}")]
    PluginNotFound(String),
    #[error("Loader error: {0}")]
    LoaderError(#[from] LoaderError),
    #[error("IO error: {0}")]
    IoError(#[from] std::io::Error),
    #[error("Dependency error: {0}")]
    DependencyError(String),
}

impl Default for PluginManager {
    fn default() -> Self {
        Self::new(true)
    }
}

impl PluginManager {
    /// Create a new plugin manager with default loaders
    #[must_use]
    pub fn new(verify_plugin_signatures: bool) -> Self {
        Self {

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