Common Issues

This page covers the problems people hit most often when bundling with Packem: nothing gets built, dependencies fail to resolve, output lands in the wrong place, or the package.json validators flag your configuration. Each section follows a problem → cause → solution structure and uses the real messages Packem emits.

No entries detected

Problem

The build stops immediately with one of:

No source files found in 'src' directory. Please provide entries manually.

No entries detected. Please provide entries manually.

Cause

Packem's auto preset infers entry points from your package.json exports, main, module, and types fields and then maps them back to source files in your source directory (src by default). If none of those fields are configured — or they point at output paths that have no matching source file — there is nothing to infer.

Solution

Configure your package.json exports so each output maps to a source file:

{
  "exports": {
    ".": {
      "import": "./dist/index.mjs",
      "require": "./dist/index.cjs"
    }
  }
}

With ./dist/index.mjs declared, Packem looks for ./src/index.ts (or .js, .tsx, etc.) and builds it. Alternatively, define entries explicitly in packem.config.ts:

import { defineConfig } from '@visulima/packem/config'
import transformer from '@visulima/packem/transformer/esbuild'

export default defineConfig({
  transformer,
  entries: ['src/index.ts']
})

Externals not resolving

Problem

The build fails with:

Failed to resolve the module "some-package" imported by "src/index.ts"
Is the module installed? Note:
 ↳ to inline a module into your bundle, install it to "devDependencies".
 ↳ to depend on a module via import/require, install it to "dependencies".

Cause

Packem treats this UNRESOLVED_IMPORT as a hard error by default. The two hints in the message are the actual fix paths: where a dependency lives in package.json determines whether it gets inlined into the bundle or left external.

By default, everything in dependencies and peerDependencies is marked external automatically and is not included in the bundle. Packages you want bundled in must be resolvable on disk.

Solution

• To bundle a module into your output, install it under devDependencies.
• To depend on a module at runtime (kept external), install it under dependencies or peerDependencies.

If you want an unresolved import to warn instead of failing the build, set unresolvedImportBehavior to "warn":

import { defineConfig } from '@visulima/packem/config'
import transformer from '@visulima/packem/transformer/esbuild'

export default defineConfig({
  transformer,
  rollup: {
    resolve: {
      unresolvedImportBehavior: 'warn'
    }
  }
})

You can also bundle declared dependencies instead of externalizing them with the CLI flag:

packem build --no-external

Output directory and file names

Problem

Files land somewhere unexpected, or you can't find the generated dist.

Cause

Packem resolves the output directory from your TypeScript config first: compilerOptions.outDir is used when present, falling back to dist. The validators also check that your package.json files field includes that directory.

Solution

If your files array does not list the output directory, Packem warns:

The 'files' field in your package.json is missing the 'dist' directory. Ensure the output directory is included.

Add it so your published package actually ships the build:

{
  "files": ["dist"]
}

To change where output goes, set outDir in compilerOptions of tsconfig.json, and keep the files field in sync.

Validation failures

Problem

The build prints package.json validation warnings, or fails outright when failOnWarn is enabled.

Cause

Packem validates package.json against what is required to publish a working package. Real warnings include:

• Missing main export ".". Subpaths exports should include a main export entry
• The 'name' field is missing in your package.json. Please provide a valid package name.
• The 'module' field is missing in your package.json, but you are emitting ES modules.
• Incorrect condition order at <path>. Standard conditions should be ordered: node-addons > node > import > require > module-sync > default
• These dependencies are listed in package.json but not used: <list>
• These dependencies are shamefully hoisted: <list>

Solution

Fix the underlying package.json field the warning points at. Conditions inside exports are order-sensitive — types must come first and default last, with import/require in between. For a clean publish, also run publint and Are the Types Wrong?.

If you need to skip validation entirely (for example, in a fast inner-loop build), pass --no-validation:

packem build --no-validation

Related

• TypeScript Problems
• CSS Issues
• Build Errors