parcel-bundler/parcel · error · ThrowableDiagnostic

The "global" output format is not supported in the "${target

Error message

The "global" output format is not supported in the "${targetName}" target.

What it means

The `global` outputFormat (IIFE-style global assignment) is rejected for the named target. Parcel only supports `global` for the `browser`-style/UMD-like scenarios tied to specific targets, and this guard fires when descriptor.outputFormat === 'global' is set on a target whose configuration disallows it (paired with a code highlight on /targets/<name>/outputFormat).

Source

Thrown at packages/core/core/src/requests/TargetRequest.js:774

                  ]),
                },
              ],
              hints: [
                `The "${targetName}" field is meant for libraries. If you meant to output a ${ext} file, either remove the "${targetName}" field or choose a different target name.`,
              ],
              documentationURL:
                'https://parceljs.org/features/targets/#library-targets',
            },
          });
        }

        if (descriptor.outputFormat === 'global') {
          let contents: string =
            typeof pkgContents === 'string'
              ? pkgContents
              : // $FlowFixMe
                JSON.stringify(pkgContents, null, '\t');
          throw new ThrowableDiagnostic({
            diagnostic: {
              message: md`The "global" output format is not supported in the "${targetName}" target.`,
              origin: '@parcel/core',
              codeFrames: [
                {
                  language: 'json',
                  filePath: pkgFilePath ?? undefined,
                  code: contents,
                  codeHighlights: generateJSONCodeHighlights(contents, [
                    {
                      key: `/targets/${targetName}/outputFormat`,
                      type: 'value',
                    },
                  ]),
                },
              ],
              hints: [
                `The "${targetName}" field is meant for libraries. The outputFormat must be either "commonjs" or "esmodule". Either change or remove the declared outputFormat.`,

View on GitHub (pinned to 59484858a1)

Solutions

Switch the target's outputFormat to a supported value (`esmodule`, `commonjs`) or use a target/context that supports `global`.
If you need a UMD/global browser bundle, ensure the target's env context is browser and remove conflicting options.
Remove the explicit outputFormat and let Parcel infer it from the target name/extension.

Example fix

// before (package.json)
"targets": {
  "main": { "outputFormat": "global" }
}

// after
"targets": {
  "main": { "outputFormat": "commonjs" }
}

Defensive patterns

Strategy: validation

Validate before calling

function assertOutputFormat(targetName, descriptor) {
  if (descriptor.outputFormat === 'global' && !/browser|umd/.test(targetName)) {
    throw new Error(`"global" outputFormat not permitted for target ${targetName}`);
  }
}

Type guard

function allowsGlobalOutputFormat(descriptor) {
  return descriptor?.outputFormat !== 'global' || descriptor?.context === 'browser';
}

Try / catch

try { await parcel.run(); } catch (e) {
  if (/"global" output format is not supported/.test(e.message)) {
    console.error('Switch outputFormat to esmodule/commonjs or use a browser target.');
  } else throw e;
}

Prevention

Avoid `outputFormat: 'global'` on Node/library targets.
Use the `module` target for ESM and `main` for CJS instead of forcing global.
Document which targets permit global format in shared config.

When it happens

Trigger: Setting `"outputFormat": "global"` under `targets.<name>` in package.json for a target that does not permit the global format (e.g. an esmodule/commonjs-only target).

Common situations: Migrating from webpack `libraryTarget: 'global'` and carrying the format over; trying to ship a UMD-ish bundle by hand-configuring global on a target that resolves to a non-browser context.

Related errors

AI-assisted analysis of parcel-bundler/parcel@59484858a1 (2026-08-13). Data as JSON: /api/errors/085551825a39df2d. Report an issue: GitHub.