emberjs/ember.js · error · Error

Cannot call `setComponentTemplate` multiple times on the sam

Error message

Cannot call `setComponentTemplate` multiple times on the same class (`${debugToString!(obj)}`)

What it means

Error "Cannot call `setComponentTemplate` multiple times on the same class (`${debugToString!(obj)}`)" thrown in emberjs/ember.js.

Source

Thrown at packages/@glimmer/manager/lib/public/template.ts:16

import { DEBUG } from '@glimmer/env';
import type { TemplateFactory } from '@glimmer/interfaces';
import debugToString from '@glimmer/debug-util/lib/debug-to-string';

const TEMPLATES: WeakMap<object, TemplateFactory> = new WeakMap();

const getPrototypeOf = Reflect.getPrototypeOf;

export function setComponentTemplate(factory: TemplateFactory, obj: object) {
  if (DEBUG && !(obj !== null && (typeof obj === 'object' || typeof obj === 'function'))) {
    // eslint-disable-next-line @typescript-eslint/no-non-null-assertion -- @fixme
    throw new Error(`Cannot call \`setComponentTemplate\` on \`${debugToString!(obj)}\``);
  }

  if (DEBUG && TEMPLATES.has(obj)) {
    throw new Error(
      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion -- @fixme
      `Cannot call \`setComponentTemplate\` multiple times on the same class (\`${debugToString!(
        obj
      )}\`)`
    );
  }

  TEMPLATES.set(obj, factory);

  return obj;
}

export function getComponentTemplate(obj: object): TemplateFactory | undefined {
  let pointer: object | null = obj;

  while (pointer !== null) {
    let template = TEMPLATES.get(pointer);

View on GitHub (pinned to 26f97246a8)

When it happens

Trigger: Thrown at packages/@glimmer/manager/lib/public/template.ts:16 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of emberjs/ember.js@26f97246a8 (2026-09-01). Data as JSON: /api/errors/7ff51deaf6e1022d. Report an issue: GitHub.