Exchange 2019: Does the January 2023 SU with CU 12 trigger the index problem again?

Exchange Logo[German]Quick question in the round, aimed at Microsoft Exchange Server administrators. Have you guys encountered any major issues (aside from services not starting automatically) when installing the January 2023 security updates? I have feedback from a service provider that the latest CU triggers the "index issue" again with Microsoft Exchange 2019. Here's a brief outline of what it's all about.


Exchange January 2023 Updates

Microsoft has released security updates for Exchange Server 2013, Exchange Server 2016, and Exchange Server 2019 as of January 10, 2023 (see Exchange Server Security Updates (January 10, 2023)). These security updates close two vulnerabilities (Elevation of Privilege and Spoofing) in this software. These updates should be installed on systems in a timely manner to close the vulnerabilities in question.

So far, I was only aware of reports from administrators complaining that after installing the January 2023 CUs, services no longer started automatically. I had addressed this in the blog post Microsoft Exchange January 2023 patchday issues. The remedy is to manually start the required services for Exchange.

Is the index issue back?

German blog reader Dennis Könn contacted me in a private message on Facebook and reported that the SU of January 2023 for Microsoft Exchange 2019 triggers the index issue again. Apparently, the indexing of mailboxes breaks in the process, so mails are no longer found. Specifically, this probably occurred with an Exchange Server 2019 running on a Windows Server 2022. Dennis has meanwhile stated that it happened with CU 12 in connection with the last security update.

I have heared from other readers, that the indexing issue has been present for years. The question remains whether other cases are known among the blog readership, or whether it was an isolated incident.

There are always problems with the search index with Microsoft Exchange Server 2019, as a search on the Internet reveals. On, for example, the older article Exchange 2019 CU12 Search Indexing issues can be found. There it says that the problem has been dragging through the CU's for some time. From 2021 there is the post Microsoft Exchange 2019 search issues since CU8 and HAFNIUM patches, which complains about something similar.


Various implementations

If I understand it correctly, Microsoft uses different implementations of indexing in Exchange Server.

  • Exchange 2013 uses Search Foundation for indexing, while Exchange 2016 uses FAST search architecture (from Sharepoint indexing). Both implementations use catalog indexing, which is, among other things, a folder located in the EDB (database file) folder.
  • Exchange 2019 uses a new architecture based on the Big Funnel search engine used in Bing, which is also already used by Exchange Online as part of Office 365 in the cloud.

Especially the latter implementation seems to be good for problems with indexing

Solutions for the index problem

If you run into the index problem with Microsoft Exchange, you need to have the index rebuilt. To that end, Tzahi Kolber's article Fixing Search/Indexing issues within Exchange 2019 mailboxes. not only outlines the differences in the indexing of Exchange Server 2013, 2016 and 2019 outlined above in the text, but the article also discusses methods for checking and repairing the search index for each Exchange version.

Also, the blog post How to Fix Big Funnel Indexing Issues in Exchange 2019 contains tips to try and fix a broken index.

Similar articled:
Exchange Server Security Updates (January 10, 2023)
Microsoft Exchange January 2023 patchday issues

Exchange isues with ECP/OWA search after installing security update (March 2021)
Exchange 2016/2019: Outlook problems due to AMSI integration
Exchange Server September 2021 CU comes Sept. 28 with Microsoft Exchange Emergency Mitigation Service
Exchange Server 2016-2019: Custom attributes in ECP no longer updatable after CU installation (July 2021)
Microsoft advises end of support for Exchange Server 2013 on April 11, 2023
Microsoft Exchange survey to improve the update process (auto update)

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