fabricjs/fabric.js · error · FabricError

No class registered for ${classType}

Error message

No class registered for ${classType}

What it means

Fabric.js keeps a registry (ClassRegistry) that maps string type names to class constructors, used when deserializing JSON (fromObject) and when resolving classes by string (getClass). When `getClass(classType)` is called with a name that was never registered via `setClass`, no constructor exists and this error is thrown. It typically means a class is not imported/registered before loading JSON that references it, or a custom class's `type` doesn't match the registered key.

Source

Thrown at packages/core/src/ClassRegistry.ts:34

export const SVG = 'svg';

export class ClassRegistry {
  declare [JSON]: Map<string, any>;
  declare [SVG]: Map<string, any>;

  constructor() {
    this[JSON] = new Map();
    this[SVG] = new Map();
  }

  has(classType: string): boolean {
    return this[JSON].has(classType);
  }

  getClass<T>(classType: string): T {
    const constructor = this[JSON].get(classType);
    if (!constructor) {
      throw new FabricError(`No class registered for ${classType}`);
    }
    return constructor;
  }

  setClass(classConstructor: any, classType?: string) {
    if (classType) {
      this[JSON].set(classType, classConstructor);
    } else {
      this[JSON].set(classConstructor.type, classConstructor);
      // legacy
      // @TODO: needs to be removed in fabric 7 or 8
      this[JSON].set(classConstructor.type.toLowerCase(), classConstructor);
    }
  }

  getSVGClass(SVGTagName: string): any {
    return this[SVG].get(SVGTagName);
  }

View on GitHub (pinned to 2bd4992cab)

Solutions

1. Import the class (or its side-effectful registration module) before calling loadFromJSON/fromObject: e.g. `import { MyCustomClass } from './MyCustomClass'` and `ClassRegistry.setClass(MyCustomClass)` / `ClassRegistry.setClass(MyCustomClass, 'MyCustom')` when using a custom type string.
2. Verify the `type` string in the JSON matches the registered key (custom `type` requires the second argument of setClass).
3. Check the bundle: ensure side-effect imports aren't stripped (`sideEffects: true` in package config or explicit `import '...'` statements).
4. If deserializing unknown types is expected, catch this error and skip or substitute a fallback object.

Example fix

// before
const json = '{"objects":[{"type":"textbox","text":"hi"}]}';
canvas.loadFromJSON(json); // throws: No class registered for textbox

// after
import { Textbox } from 'fabric'; // or the module that registers it
const json = '{"objects":[{"type":"textbox","text":"hi"}]}';
canvas.loadFromJSON(json);

import { classRegistry } from 'fabric';
const type = obj.type;
if (!classRegistry.getClass(type)) {
  console.warn(`Unknown type "${type}" in JSON; skipping or substituting.`);
} else {
  const Klass = classRegistry.getClass(type);
}

const isRegisteredType = (t: unknown): t is string =>
  typeof t === 'string' && classRegistry.getClass(t) !== undefined;

try {
  await canvas.loadFromJSON(json);
} catch (e) {
  if (e instanceof Error && e.message.startsWith('No class registered for')) {
    // import/register the missing class, or filter unknown objects out of the JSON and retry
  } else throw e;
}

When it happens

Trigger: Calling `ClassRegistry.getClass('MyClass')` (directly or via `fabric.EnlivenObjects`/`loadFromJSON`) when 'MyClass' was never passed to `ClassRegistry.setClass`. Also happens with custom classes whose static `type` differs from the string stored in JSON, or when tree-shaking removes side-effectful registration imports.

Common situations: Loading a saved canvas JSON containing a custom object type without importing that class first; renaming a custom class or its `type` string between save and load; bundler (webpack/Vite production build) dropping registration side effects; using a plugin/filter that registers itself only via a side-effect import the user forgot to add.

Related errors

• Trying to initialize a canvas that has already been initiali
• Fabric env was not initialized. Import fabric, fabric/node,
• Vertex, fragment shader or program creation error
• Vertex shader compile error for ${this.type}: ${gl.getShader
• Fragment shader compile error for ${this.type}: ${gl.getShad

AI-assisted analysis of fabricjs/fabric.js@2bd4992cab (2026-08-28). Data as JSON: /api/errors/c38367fdb8a69a0e. Report an issue: GitHub.