emberjs/ember.js · error · Error

Compile Error: ${error.problem} @ ${error.span.start}..${err

Error message

Compile Error: ${error.problem} @ ${error.span.start}..${error.span.end}

What it means

unwrapHandle converts a template compilation result into a numeric handle. When compilation failed, the first error's problem message and span are surfaced as a thrown Compile Error so template syntax mistakes fail loudly at build/broccoli time.

Source

Thrown at packages/@glimmer/debug-util/lib/template.ts:8

import type { ErrHandle, HandleResult, OkHandle, Template, TemplateOk } from '@glimmer/interfaces';

export function unwrapHandle(handle: HandleResult): number {
  if (typeof handle === 'number') {
    return handle;
  } else {
    let error = handle.errors[0];
    throw new Error(`Compile Error: ${error.problem} @ ${error.span.start}..${error.span.end}`);
  }
}

export function unwrapTemplate(template: Template): TemplateOk {
  if (template.result === 'error') {
    throw new Error(
      `Compile Error: ${template.problem} @ ${template.span.start}..${template.span.end}`
    );
  }

  return template;
}

export function extractHandle(handle: HandleResult): number {
  if (typeof handle === 'number') {
    return handle;
  } else {
    return handle.handle;

View on GitHub (pinned to 26f97246a8)

Solutions

Read the problem and span in the message to locate the template and fix the syntax
Validate the template compiles by rendering it in development where errors surface with better tooling
Check for syntax unsupported by your glimmer-vm version and upgrade if needed
Run the template through the compiler CLI/linter (ember-template-lint) before building

Example fix

// before (template)
{{#if foo}}
  <p>hi
// after
{{#if foo}}
  <p>hi</p>
{{/if}}

Defensive patterns

Strategy: try-catch

Type guard

function isHandleOk(h) { return typeof h === 'number'; }

Try / catch

try {
  let handle = unwrapHandle(result);
} catch (e) {
  if (String(e.message).startsWith('Compile Error:')) {
    console.error('Template failed to compile:', e.message);
  } else { throw e; }
}

Prevention

Run ember-template-lint in CI on all templates
Compile templates during development to catch syntax errors early
Keep glimmer-vm and template compiler versions in sync

When it happens

Trigger: Precompiling a .hbs/.gjs template containing a syntax error (unclosed tag, bad mustache, invalid block param) and then calling unwrapHandle (via handle()/layoutHandle()) on the failed result.

Common situations: Typo in handlebars syntax; unsupported syntax for the installed Glimmer version; build-time template compilation in ember-cli-build or addon precompilation pipelines.

Related errors

AI-assisted analysis of emberjs/ember.js@26f97246a8 (2026-09-01). Data as JSON: /api/errors/0c36a3a2a38042a8. Report an issue: GitHub.