hashicorp/packer · error

Error uploading ps script containing env vars

Error message

Error uploading ps script containing env vars: %s

What it means

The PowerShell provisioner flattens the configured environment variables into a .ps1 file and uploads it to RemoteEnvVarPath inside a retry loop (StartRetryTimeout). This error wraps any failure from that communicator Upload. The env-vars script never landed on the guest, so command execution that depends on it will fail or run without those variables.

Solutions

1. Inspect the wrapped cause in the message (after the colon) to see the transport-level reason.
2. Ensure the guest stays up and connected for the whole provision phase; disable guest auto-restart during builds.
3. Verify the env var script path's directory is writable by the communicator user.
4. Increase start_retry_timeout to ride out longer transient outages.
5. Retry the build; transient conditions are explicitly expected to be handled by the retry loop.

Example fix

// before
"start_retry_timeout": "5m"
// after
"start_retry_timeout": "10m"

When it happens

Trigger: communicator.Upload of the env-var .ps1 fails: transient SSH/WinRM disconnects across all retries, permission denied at RemoteEnvVarPath, guest disk full, or upload protocol errors.

Common situations: Guest reboots or loses network during provisioning; env_var_script_path's directory not writable; antivirus on Windows guests locking newly created files in temp; long builds where the session times out.

Related errors

• clean up script failed to upload
• Error uploading script
• Environment variable not in format 'key=value
• Error uploading envVarFile
• failed to upload Packer binary

AI-assisted analysis of hashicorp/packer@eb36e3c3e4 (2026-09-05). Data as JSON: /api/errors/47e9368717e75552. Report an issue: GitHub.

Appendix: source

Thrown at provisioner/powershell/provisioner.go:576

	// Re-assemble vars using OS specific format pattern and flatten
	for _, key := range keys {
		flattened += fmt.Sprintf(format, key, envVars[key])
	}
	return
}

func (p *Provisioner) uploadEnvVars(flattenedEnvVars string) (err error) {
	ctx := context.TODO()
	// Upload all env vars to a powershell script on the target build file
	// system. Do this in the context of a single retryable function so that
	// we gracefully handle any errors created by transient conditions such as
	// a system restart
	envVarReader := strings.NewReader(flattenedEnvVars)
	log.Printf("Uploading env vars to %s", p.config.RemoteEnvVarPath)
	err = retry.Config{StartTimeout: p.config.StartRetryTimeout}.Run(ctx, func(context.Context) error {
		if err := p.communicator.Upload(p.config.RemoteEnvVarPath, envVarReader, nil); err != nil {
			return fmt.Errorf("Error uploading ps script containing env vars: %s", err)
		}
		return err
	})
	return
}

func (p *Provisioner) createCommandText() (command string, err error) {
	// Return the interpolated command
	if p.config.ElevatedUser == "" {
		return p.createCommandTextNonPrivileged()
	} else {
		return p.createCommandTextPrivileged()
	}
}

func (p *Provisioner) createCommandTextNonPrivileged() (command string, err error) {
	// Prepare everything needed to enable the required env vars within the
	// remote environment

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