bumptech/glide · error · RuntimeException

Expected instanceof GlideModule, but found: {module}

Error message

Expected instanceof GlideModule, but found: {module}

What it means

Thrown by ManifestParser.parseModule after a class named in AndroidManifest meta-data was loaded and instantiated via reflection but does not implement com.bumptech.glide.module.GlideModule. The parser needs the GlideModule contract (registerComponents / applyOptions) to wire in custom behavior.

Source

Thrown at library/src/main/java/com/bumptech/glide/module/ManifestParser.java:99

      throw new IllegalArgumentException("Unable to find GlideModule implementation", e);
    }

    Object module = null;
    try {
      module = clazz.getDeclaredConstructor().newInstance();
      // These can't be combined until API minimum is 19.
    } catch (InstantiationException e) {
      throwInstantiateGlideModuleException(clazz, e);
    } catch (IllegalAccessException e) {
      throwInstantiateGlideModuleException(clazz, e);
    } catch (NoSuchMethodException e) {
      throwInstantiateGlideModuleException(clazz, e);
    } catch (InvocationTargetException e) {
      throwInstantiateGlideModuleException(clazz, e);
    }

    if (!(module instanceof GlideModule)) {
      throw new RuntimeException("Expected instanceof GlideModule, but found: " + module);
    }
    return (GlideModule) module;
  }

  private static void throwInstantiateGlideModuleException(Class<?> clazz, Exception e) {
    throw new RuntimeException("Unable to instantiate GlideModule implementation for " + clazz, e);
  }
}

View on GitHub (pinned to eb14a895d8)

Solutions

1. Make the registered class implement (or extend a base that implements) com.bumptech.glide.module.GlideModule
2. Migrate to the modern @GlideModule + AppGlideModule annotation-processor API and delete the manifest entry
3. Remove the stale meta-data entry if the class is not meant to be a Glide module
4. Verify the class has a public no-arg constructor and the correct inheritance after library upgrades

Example fix

// before
<meta-data android:name="com.example.ConfigHolder" android:value="GlideModule"/>
// ConfigHolder is a plain object, not a GlideModule

// after
class MyGlideModule : GlideModule {
  override fun applyOptions(context: Context, builder: GlideBuilder) { /* ... */ }
  override fun registerComponents(context: Context, glide: Glide, registry: Registry) { /* ... */ }
}

val module: Any = clazz.getDeclaredConstructor().newInstance()
require(module is GlideModule) { "${clazz.name} is not a GlideModule" }

fun isGlideModule(clazz: Class<*>): Boolean =
  com.bumptech.glide.module.GlideModule::class.java.isAssignableFrom(clazz)

When it happens

Trigger: Registering a plain class, a data holder, or a class implementing a different interface under android:value="GlideModule" in the manifest. The class loads and constructs fine, but fails the instanceof GlideModule check at ManifestParser.java:99.

Common situations: Copy-paste of a meta-data entry with the wrong class; a module class that extends a base class which no longer implements GlideModule after a library update; using an AppGlideModule (the new API) name in the old manifest meta-data path.

Related errors

• Unable to find GlideModule implementation
• Unable to instantiate GlideModule implementation for {clazz}
• You cannot start a load on a fragment before it is attached
• sizeMultiplier must be between 0 and 1
• You cannot auto lock an already locked options object, try c

AI-assisted analysis of bumptech/glide@eb14a895d8 (2026-08-14). Data as JSON: /api/errors/5284d38a11c0d033. Report an issue: GitHub.