What causes "timeout - last error: %v" in hashicorp/terraform?

Raise the 'timeout' in the connection block (e.g. timeout = "10m").

timeout - last error: %v

Error message

timeout - last error: %v

What it means

Same Retry loop as 777, but the context hit its deadline (context.DeadlineExceeded) at communicator.go:165. The last retryable error is included so you can see why retries kept failing. This is governed by the provisioner/connection timeout.

Source

Thrown at internal/communicator/communicator.go:166

	// Wait for completion
	select {
	case <-ctx.Done():
	case <-doneCh:
	}

	var lastErr error
	// Check if we got an error executing
	if ev, ok := errVal.Load().(errWrap); ok {
		lastErr = ev.E
	}

	// Check if we have a context error to check if we're interrupted or timeout
	switch ctx.Err() {
	case context.Canceled:
		return fmt.Errorf("interrupted - last error: %v", lastErr)
	case context.DeadlineExceeded:
		return fmt.Errorf("timeout - last error: %v", lastErr)
	}

	if lastErr != nil {
		return lastErr
	}
	return nil
}

View on GitHub (pinned to c9def3e214)

Solutions

Raise the 'timeout' in the connection block (e.g. timeout = "10m").
Verify host reachability, open ports, and firewall/security-group rules.
Address the appended 'last error' (auth, network, DNS) so retries succeed before the deadline.

Example fix

// before
connection {
  type    = "ssh"
  user    = "ubuntu"
  host    = aws_instance.web.public_ip
  timeout = "30s"
}
Error: timeout - last error: dial tcp ...: i/o timeout

// after
connection {
  type    = "ssh"
  user    = "ubuntu"
  host    = aws_instance.web.public_ip
  timeout = "10m"
}

Defensive patterns

Strategy: try-catch

Validate before calling

// Size the timeout to the worst-case remote op, not the happy path.
timeout := 5 * time.Minute // raise as needed for slow hosts
ctx, cancel := context.WithTimeout(parentCtx, timeout)
defer cancel()

Type guard

null

Try / catch

err := communicator.Retry(ctx, func() error { return c.Connect(o) })
if err != nil && errors.Is(ctx.Err(), context.DeadlineExceeded) {
    // distinguish 'timeout' from a hard auth failure and guide the user
}

Prevention

Set a generous connection/command timeout for slow or ephemeral hosts.
Pre-flight check host reachability (port open, security groups) before provisioning.
Address the underlying retryable error so retries succeed before the deadline.

When it happens

Trigger: The retry context deadline elapses before f succeeds — the provisioner 'timeout' argument or the command timeout was exceeded while the remote op kept failing.

Common situations: Slow or unreachable remote host; flaky network; long-running remote command exceeding the configured timeout; sshd slow to start on a freshly-booted instance.

Understand the failure class

Timeouts: ETIMEDOUT, deadlines, and hung requests — what actually expires when a request times out.

Related errors

AI-assisted analysis of hashicorp/terraform@c9def3e214 (2026-08-07). Data as JSON: /api/errors/2f37bd5e2a272004. Report an issue: GitHub.