Unable to create installed.flag file in ${packageInstallFold

Error message

Unable to create installed.flag file in ${packageInstallFolder}

What it means

After npm install completes, _writeFlagFile writes an installed.flag file into the package install folder to mark it cached. If writeFileSync fails (permissions, full disk, read-only filesystem, missing directory), this error is thrown. It means the install succeeded or ran, but the cache marker could not be persisted.

Source

Thrown at foundations/net/common/scripts/install-run.js:678

/**
 * Returns a cross-platform path - windows must enclose any path containing spaces within double quotes.
 */
function _getPlatformPath(platformPath) {
    return _isWindows() && platformPath.includes(' ') ? `"${platformPath}"` : platformPath;
}
function _isWindows() {
    return os__WEBPACK_IMPORTED_MODULE_2__.platform() === 'win32';
}
/**
 * Write a flag file to the package's install directory, signifying that the install was successful.
 */
function _writeFlagFile(packageInstallFolder) {
    try {
        const flagFilePath = path__WEBPACK_IMPORTED_MODULE_3__.join(packageInstallFolder, INSTALLED_FLAG_FILENAME);
        fs__WEBPACK_IMPORTED_MODULE_1__.writeFileSync(flagFilePath, process.version);
    }
    catch (e) {
        throw new Error(`Unable to create installed.flag file in ${packageInstallFolder}`);
    }
}
function installAndRun(logger, packageName, packageVersion, packageBinName, packageBinArgs, lockFilePath = process.env[INSTALL_RUN_LOCKFILE_PATH_VARIABLE]) {
    const rushJsonFolder = findRushJsonFolder();
    const rushCommonFolder = path__WEBPACK_IMPORTED_MODULE_3__.join(rushJsonFolder, 'common');
    const rushTempFolder = _getRushTempFolder(rushCommonFolder);
    const packageInstallFolder = _ensureAndJoinPath(rushTempFolder, 'install-run', `${packageName}@${packageVersion}`);
    if (!_isPackageAlreadyInstalled(packageInstallFolder)) {
        // The package isn't already installed
        _cleanInstallFolder(rushTempFolder, packageInstallFolder, lockFilePath);
        const sourceNpmrcFolder = path__WEBPACK_IMPORTED_MODULE_3__.join(rushCommonFolder, 'config', 'rush');
        (0,_utilities_npmrcUtilities__WEBPACK_IMPORTED_MODULE_4__.syncNpmrc)({
            sourceNpmrcFolder,
            targetNpmrcFolder: packageInstallFolder,
            logger,
            supportEnvVarFallbackSyntax: false
        });
        _createPackageJson(packageInstallFolder, packageName, packageVersion);

View on GitHub (pinned to 63e28dc964)

Solutions

Check write permissions on the rush temp/common install folder and fix ownership (chown/chmod) or run as a user who can write there.
Delete the stale package install folder and re-run so it is recreated with correct permissions.
Free disk space if the volume is full.
Avoid running concurrent builds that share the same rush cache folder, or point INSTALL_RUN_LOCKFILE_PATH / cache to a writable location.

Example fix

// before: ~/.rush owned by root, build runs as ci user
sudo chown -R $(whoami) ~/.rush
node common/scripts/install-run-rush.js build
// after: cache writable by the build user, script succeeds

Defensive patterns

Strategy: validation

Validate before calling

const fs = require('fs');
function cacheFolderWritable(folder) {
  try { fs.mkdirSync(folder, { recursive: true }); fs.accessSync(folder, fs.constants.W_OK); return true; }
  catch { return false; }
}

Try / catch

try {
  await runInstallRunScript(args);
} catch (e) {
  if (String(e.message).startsWith('Unable to create installed.flag')) {
    const folder = e.message.match(/in (.+)$/)?.[1];
    console.error(`Cannot write to ${folder}: check permissions/disk space`);
    process.exit(1);
  }
  throw e;
}

Prevention

Run builds as a user that owns the rush cache folder (~/.rush).
Never mount the cache directory read-only.
Monitor disk space on CI runners.
Avoid concurrent builds sharing one rush temp folder.

When it happens

Trigger: Running an install-run shim script when fs.writeFileSync cannot create installed.flag inside the rush temp package folder — e.g. directory owned by root/another user, read-only mount, or the folder was deleted mid-run.

Common situations: CI containers running as non-root but reusing a root-owned ~/.rush cache; Docker volumes mounted read-only; disk-quota exhaustion; multiple concurrent builds racing on the same temp folder.

Understand the failure class

Background: Permission denied / not authorized / 403 Forbidden: access-control rejections when the caller lacks the required role, grant, or ownership — this error's family across 18 libraries.

Related errors

AI-assisted analysis of hcengineering/platform@63e28dc964 (2026-08-29). Data as JSON: /api/errors/98d7e0a5d258faf4. Report an issue: GitHub.