CA Backup and Restore Windows PowerShell cmdlets

Article
05/17/2023

Applies to: Windows Server 2022, Windows Server 2019, Windows Server 2016, Windows Server 2012 R2, Windows Server 2012

Author: Justin Turner, Senior Support Escalation Engineer with the Windows group

Note

This content is written by a Microsoft customer support engineer, and is intended for experienced administrators and systems architects who are looking for deeper technical explanations of features and solutions in Windows Server 2012 R2 than topics on TechNet usually provide. However, it has not undergone the same editing passes, so some of the language may seem less polished than what is typically found on TechNet.

Overview

The ADCSAdministration Windows PowerShell module was introduced in Window Server 2012. Two new cmdlets were added to this module in Window Server 2012 R2 to support the Backup and Restore of a CA.

Backup-CARoleService
Restore-CARoleService

Backup-CARoleService

ADCSAdministration Cmdlet: Backup-CARoleService

Arguments - Bold arguments are required	Description
-Path	- String - location to save the backup - This is the only unnamed parameter - positional parameter Example: Backup-CARoleService.-Path c:\adcsbackup1 Backup-CARoleService c:\adcsbackup2
-KeyOnly	- Backup the CA certificate without the database Example: Backup-CARoleService c:\adcsbackup3 -KeyOnly
-Password	- Specifies the password to protect CA certificates and private keys - Must be a secure string - Not valid with the -DatabaseOnly parameter Example: Backup-CARoleService c:\adcsbackup4 -Password (Read-Host -prompt "Password:" -AsSecureString) Backup-CARoleService c:\adcsbackup5 -Password (ConvertTo-SecureString "Pa55w0rd!" -AsPlainText -Force)
-DatabaseOnly	- Backup the database without the CA certificate Backup-CARoleService c:\adcsbackup6 -DatabaseOnly
-Force	1. Allows you to overwrite the backup that pre-exists in the location specified in the -Path parameter Backup-CARoleService c:\adcsbackup1 -Force
-Incremental	- Perform an incremental backup Backup-CARoleService c:\adcsbackup7 -Incremental
-KeepLog	1. Instructs the command to keep log files. If the switch isn't specified, log files are truncated by default except in the Incremental scenario Backup-CARoleService c:\adcsbackup7 -KeepLog

-Password <Secure String>

If the -Password parameter is used, the supplied password must be a secure string. Use the Read-Host cmdlet to launch an interactive prompt for secure password entry, or use the ConvertTo-SecureString cmdlet to specify the password in-line.

Review the following examples

Specifying a secure string for the Password parameter using Read-Host

Backup-CARoleService c:\adcsbackup4 -Password (Read-Host -prompt "Password:" -AsSecureString)

Specifying a secure string for the Password parameter using ConvertTo-SecureString

Backup-CARoleService c:\adcsbackup5 -Password (ConvertTo-SecureString "Pa55w0rd!" -AsPlainText -Force)

Restore-CARoleService

ADCSAdministration Cmdlet: Restore-CARoleService

Arguments - Bold arguments are required	Description
-Path	- String - location to restore backup from - This is the only unnamed parameter - positional parameter Example: Restore-CARoleService.-Path c:\adcsbackup1 -Force Restore-CARoleService c:\adcsbackup2 -Force
-KeyOnly	- Restore the CA certificate without the database - Must be specified if the backup was taken with the -KeyOnly option Example: Restore-CARoleService c:\adcsbackup3 -KeyOnly -Force
-Password	- Specifies the password of the CA certificates and private keys - Must be a secure string Example: Restore-CARoleService c:\adcsbackup4 -Password (read-host -prompt "Password:" -AsSecureString) -Force Restore-CARoleService c:\adcsbackup5 -Password (ConvertTo-SecureString "Pa55w0rd!" -AsPlainText -Force) -Force
-DatabaseOnly	- Restore the database without the CA certificate Restore-CARoleService c:\adcsbackup6 -DatabaseOnly
-Force	- Allows you to overwrite the preexisting keys - Is an optional parameter but when restoring in-place, it is likely required Restore-CARoleService c:\adcsbackup1 -Force

Issues

A nonpassword protected backup is taken if the ConvertTo-SecureString function fails while using the Backup-CARoleService with the -Password parameter.

CA backup and restore

Common errors

Action	Error	Comment
Restore-CARoleService C:\ADCSBackup	Restore-CARoleService : The process can't access the file because it's being used by another process. (Exception from HRESULT: 0x80070020)	Stop the Active Directory Certificate Services service prior to running the Restore-CARoleService cmdlet
Restore-CARoleService C:\ADCSBackup	Restore-CARoleService : The directory isn't empty. (Exception from HRESULT: 0x80070091)	Use the -Force parameter to overwrite preexisting keys
Backup-CARoleService C:\ADCSBackup -Password (Read-Host -Prompt "Password:" -AsSecureString) -DatabaseOnly	Backup-CARoleService : Parameter set can't be resolved using the specified named parameters.	The -Password parameter is only used to password protect private keys and is therefore invalid when you aren't backing them up
Restore-CARoleService C:\ADCSBack15 -Password (Read-Host -Prompt "Password:" -AsSecureString) -DatabaseOnly	Restore-CARoleService : Parameter set can't be resolved using the specified named parameters.	The -Password parameter is only used to password protect private keys and is therefore invalid when you aren't restoring them
Restore-CARoleService C:\ADCSBack14 -Password (Read-Host -Prompt "Password:" -AsSecureString)	Restore-CARoleService : The system can't find the file specified. (Exception from HRESULT: 0x80070002)	The path specified doesn't contain a valid database backup. Perhaps the path is invalid or the backup was taken with the -KeysOnly option?