reachable postgres does not use the expected embedded data…

Error message

reachable postgres does not use the expected embedded data directory

What it means

Error "reachable postgres does not use the expected embedded data directory" thrown in paperclipai/paperclip.

Solutions

Point the app at the correct embedded data directory or remove the stale directory so a fresh embedded instance is initialized.
If another Postgres already uses that port, set DATABASE_URL to it explicitly.

When it happens

Trigger: Thrown at packages/db/src/migration-runtime.ts:112 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of paperclipai/paperclip@120ae5428f (2026-08-18). Data as JSON: /api/errors/5cfd9ee2f2b59c13. Report an issue: GitHub.

Appendix: source

Thrown at packages/db/src/migration-runtime.ts:112

): Promise<MigrationConnection> {
  const EmbeddedPostgres = await loadEmbeddedPostgresCtor();
  await prepareEmbeddedPostgresNativeRuntime();
  const selectedPort = await findAvailablePort(preferredPort);
  const postmasterPidFile = path.resolve(dataDir, "postmaster.pid");
  const pgVersionFile = path.resolve(dataDir, "PG_VERSION");
  const runningPid = readRunningPostmasterPid(postmasterPidFile);
  const runningPort = readPidFilePort(postmasterPidFile);
  const preferredAdminConnectionString = `postgres://paperclip:paperclip@127.0.0.1:${preferredPort}/postgres`;
  const logBuffer = createEmbeddedPostgresLogBuffer();

  if (!runningPid && existsSync(pgVersionFile)) {
    try {
      const actualDataDir = await getPostgresDataDirectory(preferredAdminConnectionString);
      const matchesDataDir =
        typeof actualDataDir === "string" &&
        path.resolve(actualDataDir) === path.resolve(dataDir);
      if (!matchesDataDir) {
        throw new Error("reachable postgres does not use the expected embedded data directory");
      }
      await ensurePostgresDatabase(preferredAdminConnectionString, "paperclip");
      process.emitWarning(
        `Adopting an existing PostgreSQL instance on port ${preferredPort} for embedded data dir ${dataDir} because postmaster.pid is missing.`,
      );
      return {
        connectionString: `postgres://paperclip:paperclip@127.0.0.1:${preferredPort}/paperclip`,
        source: `embedded-postgres@${preferredPort}`,
        stop: async () => {},
      };
    } catch {
      // Fall through and attempt to start the configured embedded cluster.
    }
  }

  if (runningPid) {
    const port = runningPort ?? preferredPort;
    const adminConnectionString = `postgres://paperclip:paperclip@127.0.0.1:${port}/postgres`;

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