# Exchange Server SE Upgrade from 2019 CU15: In-Place Steps Source: https://srvscripts.com/guides/exchange-server-se-upgrade/ Updated: 2026-10-06 Publisher: srvScripts (https://srvscripts.com/) **Short answer:** Exchange Server Subscription Edition (SE) RTM is code-equivalent to Exchange 2019 CU15, so a server already on Exchange 2019 CU14 or CU15 can be upgraded in place by running SE `Setup.exe /Mode:Upgrade` like a cumulative update, one server at a time with DAG maintenance mode. Exchange 2016 needs a legacy (side-by-side) migration. Exchange 2016 and 2019 left support on October 14, 2025, and SE needs an active entitlement: Software Assurance on your Exchange server licenses and CALs, or a qualifying Microsoft 365 subscription with on-premises server rights. Commands checked against the official documentation (linked below) on 6 October 2026; not yet run on our lab servers. ## What changed with Exchange Server SE Exchange SE replaces the old “buy a version, run it for ten years” model with a subscription-style product that keeps receiving cumulative updates as long as you keep an active entitlement. Key facts from Microsoft’s documentation: - **SE RTM (build 15.2.2562.17, July 1, 2025) has the same code as Exchange 2019 CU15.** The only differences are the license agreement, the product name and the build number. New features start with SE CU1. - **Exchange 2016 and 2019 reached end of support on October 14, 2025.** Only customers in Microsoft’s paid Extended Security Update (ESU) program receive security updates for them after that. - **Coexistence is being tightened.** SE RTM setup refuses to install into an organization that still has Exchange 2013. SE CU2 setup will refuse to coexist with any Exchange version that is unsupported at the time CU2 ships. - **Product key.** SE RTM does not need a new product key and keeps working after an in-place or legacy upgrade. Microsoft says a future SE CU will introduce a new product key requirement. - **AD schema.** Microsoft’s schema table lists the same rangeUpper and objectVersion values for SE RTM as for Exchange 2019 CU15, so an organization already prepared for CU15 has no schema change for SE RTM. As of 6 October 2026, Microsoft’s build-number list shows SE RTM with monthly security updates (the latest being SE RTM Sep26SUv2, 15.2.2562.53, released October 2, 2026). Check that page for newer releases before you plan. ## Licensing basics Microsoft’s Exchange licensing FAQ describes SE as entitlement-based. You need, and must keep: - Either active **Software Assurance** on your Exchange Server Standard or Enterprise server licenses, or a qualifying **Microsoft 365 subscription** (Microsoft names E3 or E5 acquired through an Enterprise Agreement) that includes on-premises server use rights. - A **Standard CAL** for every user or device, plus an **Enterprise CAL** for advanced features. CALs must also be covered by active SA or an equivalent qualifying Microsoft 365 subscription. Letting SA or the subscription lapse means you are no longer entitled to run SE or receive its cumulative updates. Pricing depends on your agreement; confirm entitlements with your Microsoft licensing partner before the upgrade, not after. ## Choose your upgrade path | You run today | Path to SE | | --- | --- | | Exchange 2019 CU14 or CU15 | In-place upgrade with SE setup, server by server | | Exchange 2019 CU13 or earlier | Update to CU14 or CU15 first, then in-place to SE, or do a legacy migration | | Exchange 2016 | Legacy upgrade: install new SE (or 2019 CU14/CU15) servers, move mailboxes, decommission 2016 | | Exchange 2013 still present | Remove Exchange 2013 completely first; SE setup blocks coexistence with it | | Exchange on Windows Server 2016 or older OS | Legacy migration to new servers; SE supports Windows Server 2019, 2022 and 2025 | In-place upgrades of the operating system under Exchange (for example Windows Server 2022 to 2025) are not supported. If you want a newer OS, build new servers and migrate. Check the current build of every server first: ``` # Exchange Management Shell Get-ExchangeServer | Format-Table Name, Edition, AdminDisplayVersion -AutoSize # Exact build including security/hotfix updates, run on each server Get-Command ExSetup.exe | ForEach-Object { $_.FileVersionInfo } | Select-Object ProductVersion, FileName ``` Exchange 2019 CU15 shows as `15.2.1748.x`. Microsoft recommends its Exchange HealthChecker script for a full picture of builds, settings and known issues before and after the upgrade. ## Prepare before the in-place upgrade - Read the SE release notes and the Exchange supportability matrix for your OS, .NET Framework and Visual C++ prerequisites. - Have a tested backup of Active Directory and of each Exchange server and its databases. - If a **Windows Server 2025** DC holds the Schema Master role, Microsoft requires the November 2025 or later cumulative update on it before any PrepareAD operation, to prevent AD replication issues. - Record customizations: IIS and Exchange `web.config`/`EdgeTransport.exe.config` edits and OS TLS/cipher settings are overwritten by setup. Exchange 2019 CU13 and later back up and restore the most common configuration files, but not everything. - Reboot each server before you start, use an elevated prompt, and temporarily disable antivirus during setup, as Microsoft’s CU guidance recommends. - Budget about three hours per server (Microsoft’s estimate for a CU). An Exchange CU upgrade cannot be rolled back: uninstalling it removes Exchange from the server entirely. Make sure the backups above exist and that you can rebuild the server (recover mode) if setup fails. ## Upgrade one server at a time For a DAG member, put the server into maintenance mode first. These are the commands from Microsoft’s DAG management article, run in the Exchange Management Shell; `EX01` is the server being upgraded and `EX02.contoso.com` a server that takes its queued mail: ``` Set-ServerComponentState EX01 -Component HubTransport -State Draining -Requester Maintenance Restart-Service MSExchangeTransport # on EX01 Redirect-Message -Server EX01 -Target EX02.contoso.com Set-Location $exscripts .\StartDagServerMaintenance.ps1 -ServerName EX01 -MoveComment Maintenance -PauseClusterNode Set-ServerComponentState EX01 -Component ServerWideOffline -State Inactive -Requester Maintenance Get-ServerComponentState EX01 | Format-Table Component, State -AutoSize Get-Queue ``` When queues on EX01 are empty and the components show inactive, mount the SE ISO on EX01 and run setup from an elevated command prompt (pick DiagnosticDataON or OFF): ``` D:\Setup.exe /IAcceptExchangeServerLicenseTerms_DiagnosticDataOFF /Mode:Upgrade ``` The old `/IAcceptExchangeServerLicenseTerms` switch no longer works; you must use one of the two DiagnosticData variants. The GUI route is the same: run `Setup.exe`, choose upgrade, accept the new SE license and fix anything the readiness checks report. Restart the server when setup finishes, then take it out of maintenance: ``` Set-ServerComponentState EX01 -Component ServerWideOffline -State Active -Requester Maintenance Set-Location $exscripts .\StopDagServerMaintenance.ps1 -serverName EX01 Set-ServerComponentState EX01 -Component HubTransport -State Active -Requester Maintenance Restart-Service MSExchangeTransport # on EX01 Get-ServerComponentState EX01 | Format-Table Component, State -AutoSize ``` Rebalance databases across the DAG once all members are done. Upgrade Edge Transport servers too, and update the Exchange Management Tools on admin workstations. ## Check that it worked ``` Get-ExchangeServer | Format-Table Name, Edition, AdminDisplayVersion -AutoSize Get-Command ExSetup.exe | ForEach-Object { $_.FileVersionInfo } | Select-Object ProductVersion Test-ServiceHealth EX01 Get-MailboxDatabaseCopyStatus -Server EX01 | Format-Table Name, Status, CopyQueueLength, ContentIndexState ``` - Build shows `15.2.2562.x` and the product name is Exchange Server Subscription Edition. - All required services are running and database copies are Healthy with low queues. - Outlook, OWA, ActiveSync and SMTP in both directions work; check one mailbox on each database. - Re-apply any customizations setup did not preserve, then install the latest SE security update for your build. ## Common problems - **Setup blocks because Exchange 2013 is still in the organization.** Expected with SE RTM. Decommission Exchange 2013 fully (including leftover objects) and rerun. - **Readiness check fails on prerequisites.** Install the components listed in Microsoft’s current Exchange Server prerequisites article for your OS, reboot, and retry. - **OWA or ECP errors after setup.** Usually a lost `web.config` customization or a stale OWA virtual directory setting. Compare with your notes and the configuration preservation list. - **Mail stuck in queues.** HubTransport was left in Draining. Check `Get-ServerComponentState` and set it Active. - **Hybrid environments.** After the upgrade, test free/busy, mailbox moves and mail flow with Exchange Online before you upgrade the next server. **Official documentation:** [Upgrading to Exchange Server SE](https://learn.microsoft.com/en-us/exchange/plan-and-deploy/deploy-new-installations/upgrade-to-exchange-server-se) · [What’s new in Exchange Server SE](https://learn.microsoft.com/en-us/exchange/new-features/new-features) · [Upgrade Exchange to the latest Cumulative Update](https://learn.microsoft.com/en-us/exchange/plan-and-deploy/install-cumulative-updates) · [Exchange licensing FAQ](https://www.microsoft.com/en-us/microsoft-365/exchange/microsoft-exchange-licensing-faq-email-for-business) **Related:** [Microsoft 365 SPF DKIM DMARC: Secure Exchange Online Setup](/guides/microsoft-365-spf-dkim-dmarc-exchange-online/) · [Microsoft 365 shared mailbox vs distribution group vs Microsoft 365 Group](/guides/shared-mailbox-vs-distribution-group/) · [Windows Server 2025 In-Place Upgrade: Safe Steps from 2012 R2 to 2022](/guides/windows-server-2025-in-place-upgrade/) · [Restore Domain Controller Backups: System State and DSRM Steps](/guides/backup-restore-domain-controller/) · [SMTP Test: Free STARTTLS, Certificate and Banner Check](/tools/smtp-test/) **See also:** [Exchange Online Message Trace PowerShell: Get-MessageTraceV2](/guides/exchange-online-message-trace-powershell/) · [Exchange Online Message Trace to CSV: Get-MessageTraceV2 Script](/scripts/exo-message-trace-report/) · [Exchange Online Mailbox Permissions Report: FullAccess, SendAs](/scripts/exo-mailbox-permissions-report/) ## Frequently asked questions ### Can I upgrade Exchange 2019 CU15 to SE in place? Yes. Microsoft supports an in-place upgrade from Exchange 2019 CU14 or CU15, done like a cumulative update with Setup.exe /Mode:Upgrade. ### Can I upgrade Exchange 2016 directly to SE? Not in place. You need a legacy upgrade: build SE (or 2019 CU14/CU15) servers, move mailboxes and decommission the 2016 servers. ### Does Exchange SE need a new product key? Not for SE RTM; existing keys keep working after the upgrade. Microsoft says a future SE CU will add a new product key requirement. ### Is Exchange SE free with my existing Exchange 2019 licenses? Only if those server licenses and CALs are covered by active Software Assurance, or you have a qualifying Microsoft 365 subscription with on-premises server rights. Without that entitlement you are not licensed to run SE. ### Does the upgrade change the AD schema? Not from Exchange 2019 CU15: Microsoft lists identical schema and object version values for SE RTM and 2019 CU15. Earlier versions need the usual PrepareSchema and PrepareAD steps.