remix-run/remix · error · Error

Postgres connection string must be a valid URL to resolve th

Error message

Postgres connection string must be a valid URL to resolve the maintenance database

What it means

When deriving a maintenance-database connection string, the driver must swap the database path inside the URL via the URL API. If the configured connectionString is not parseable as a URL, this error is thrown with the underlying parse failure as `cause`.

Source

Thrown at packages/data-table-postgres/src/lib/driver.ts:531

  }

  return database
}

function replaceDatabaseInConnectionString(
  connectionString: string | undefined,
  database: string,
): string | undefined {
  if (!connectionString) {
    return undefined
  }

  let url: URL

  try {
    url = new URL(connectionString)
  } catch (cause) {
    throw new Error(
      'Postgres connection string must be a valid URL to resolve the maintenance database',
      { cause },
    )
  }

  url.pathname = '/' + encodeURIComponent(database)
  return url.toString()
}

function resolveDatabaseNameFromConnectionString(
  connectionString: string | undefined,
): string | undefined {
  if (!connectionString) {
    return undefined
  }

  try {
    let url = new URL(connectionString)

View on GitHub (pinned to 9696913134)

Solutions

1. Use a full URL form: postgresql://user:password@host:5432/database
2. Percent-encode special characters in the password/username (encodeURIComponent)
3. Validate the string with `new URL(cs)` at startup/config load to fail fast with a clear message

Example fix

// before
{ connectionString: 'localhost:5432/app' } // throws

// after
{ connectionString: 'postgresql://user:pass@localhost:5432/app' }

try { new URL(connectionString) } catch { throw new Error('connectionString must be a valid postgresql:// URL') }

function isValidConnectionString(cs: string): boolean { try { new URL(cs); return true } catch { return false } }

catch (e) { if (e.cause instanceof TypeError) {/* malformed URL — fix the string */} throw e }

When it happens

Trigger: Passing a malformed connection string (missing scheme, stray characters, unencoded spaces/userinfo) in config.connectionString; strings like 'localhost:5432/db' without the postgres:// scheme; secrets with special characters breaking URL parsing.

Common situations: Copy-pasted connection strings missing the postgresql:// prefix; passwords containing '@' or '/' not percent-encoded; template strings producing 'undefined' segments.

Related errors

• mounts keys must be URL pathnames without query strings, fra
• mounts keys must not overlap. Received "${mount.urlRootKey}"
• Postgres database + method + () requires config-based const
• Postgres database config requires a database name
• throw new AssertionError({ message, actual, expected, operat

AI-assisted analysis of remix-run/remix@9696913134 (2026-08-27). Data as JSON: /api/errors/7204d6403ea53ea6. Report an issue: GitHub.