Exchange server the mailbox server role isn't installed on this computer

Question

Hello,

I have 2 DCs Windows Server 2019 (forest level 2016) & single node Exchange Server 2019 no CUs. Everything is stable including Exchange.

We want to upgrade to CU 8 and getting an error on checking prerequisites.

"The Mailbox server role isn't installed on this computer."

We run the setup directly without the 3 commands ( /PrepareSchema, /PrepareAD & /PrepareDomains). Once I take full backup for DCs and Exchange will run the commands and try again.

Did anyone faced similar issue and they got it working please assist.

Regards,

Answer 1

Yes, run each commands separately, BUT
You should be installing CU11 plus the latest Security Update, not CU8

https://www.microsoft.com/en-us/download/details.aspx?id=103477

https://support.microsoft.com/en-us/topic/description-of-the-security-update-for-microsoft-exchange-server-2019-and-2016-october-12-2021-kb5007012-de43d01b-d54f-4b40-91d1-93525a29437c

Answer 2

Hi @Ahmed Al-Takrouri

Are the 2DCs in different sites?
And is the DC with FSMO roles in a different site with the Exchange server?

If it is the case, you may either run /PrepareSchema, /PrepareAD & /PrepareDomains commands in the site where the DC hosting FSMO roles locates and wait for the AD replication to complete.
Or move the FSMO roles to the DC which is in the same site with the Exchange server.

Anyway, it is recommended to run these commands first before you install a CU update.

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