microsoft/TypeScript · error · Error

Expected to be a directory

Error message

Expected ${inputDir} to be a directory

What it means

produceLKG.mjs copies each localization directory from `source` to `dest`. For every name in localizationDirectories it stats the source path and throws if it isn't a directory, so a partial localization build can't be copied into the LKG.

Solutions

1. Run the full localization build before invoking produceLKG.
2. Inspect the path in the error message and ensure it exists as a directory.
3. Clean `built/` (`git clean -fdx built/`) and rebuild end-to-end.

import fs from "fs";
for (const d of localizationDirectories) {
  const p = path.join(source, d);
  const st = fs.statSync(p);
  if (!st.isDirectory()) throw new Error(`Expected ${p} to be a directory`);
}

When it happens

Trigger: A name in localizationDirectories resolves to a non-existent path or a file rather than a directory under `source`.

Common situations: Skipping the localize/L10n build step; a stray file where a directory is expected; previous build left inconsistent state.

Related errors

• Cannot replace the LKG unless all built targets are present…
• Expected to be a file
• Diagnostic code appears more than once.
• LKG cannot be created when --bundle=false
• patch does not match.

AI-assisted analysis of microsoft/TypeScript@b465fdbfe1 (2026-08-12). Data as JSON: /api/errors/5d56e9767d5e3a49. Report an issue: GitHub.

Appendix: source

Thrown at scripts/produceLKG.mjs:34

    console.log(`Building LKG from ${source} to ${dest}`);
    await fs.promises.rm(dest, { recursive: true, force: true });
    await fs.promises.mkdir(dest, { recursive: true });
    await copyLibFiles();
    await copyLocalizedDiagnostics();
    await copyTypesMap();
    await copyScriptOutputs();
    await copyDeclarationOutputs();
    await writeGitAttributes();
}

async function copyLibFiles() {
    await copyFilesWithGlob("lib?(.*).d.ts");
}

async function copyLocalizedDiagnostics() {
    for (const d of localizationDirectories) {
        const inputDir = path.join(source, d);
        if (!fs.statSync(inputDir).isDirectory()) throw new Error(`Expected ${inputDir} to be a directory`);
        const outputDir = path.join(dest, d);
        await fs.promises.mkdir(outputDir, { recursive: true });
        for (const f of await fs.promises.readdir(inputDir)) {
            const inputFile = path.join(inputDir, f);
            if (!fs.statSync(inputFile).isFile()) throw new Error(`Expected ${inputFile} to be a file`);
            const outputFile = path.join(outputDir, f);
            await fs.promises.copyFile(inputFile, outputFile);
        }
    }
}

async function copyTypesMap() {
    await copyFromBuiltLocal("typesMap.json"); // Cannot accommodate copyright header
}

async function copyScriptOutputs() {
    await copyFromBuiltLocal("tsc.js");
    await copyFromBuiltLocal("_tsc.js");

View on GitHub (pinned to b465fdbfe1)