SQL Server 2025 CU1 is Off to a Rough Start
SQL Server 2025 Cumulative Update 1 came out last week, and I was kinda confused by the release notes. They described a couple dozen fixed issues, and the list seemed really short for a CU1.
However, the more I dug into it, the weirder things got. For example, there were several new DMVs added – which is normally a pretty big deal, something to be celebrated in the release notes – but they weren’t mentioned in the release notes. One of the DMVs wasn’t even documented. So I didn’t blog to tell you about CU1, dear reader, because something about it seemed fishy.
Sure enough, Microsoft just pulled 2025 CU1 and 2022 CU23 because of an issue with database mail:
Database Mail stops working after you install this cumulative update. You might see the following error message:
Could not load file or assembly ‘Microsoft.SqlServer.DatabaseMail.XEvents, Version=17.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91’ or one of its dependencies. The system cannot find the file specified.
If you use Database Mail and already downloaded this update, don’t install it until a fix is available.
If you already installed this update, uninstall it to restore Database Mail functionality.
If you’ve already installed one of the affected CUs, and you need an emergency workaround fix until you can uninstall the Cumulative Update, check out this learn.microsoft.com post. Down in the answers, there’s a workaround with a PowerShell script to poll for unsent emails and send them manually. (I haven’t used this personally so I can’t vouch for it, but hey, any port in a storm.)
17 Comments. Leave new
[…] Brent Ozar notes some problems: […]
I started skeptical yet secretly hopeful MS would get its act together for this version, but my days of being unimpressed with Nadella’s Microsoft quality standards are coming to a middle.
And the exact same Database Mail problem is included – free of charge – in SQL Server 2022 CU23 🙂
Did anyone notice waaay worse performance for some functions and stored procs? especially when using MERGE, we’re moving from 2019 to 2025 on our DEV environment.
Sorry if a bit off-topic…
Is it just me, or are 3rd party vendors and associated Microsoft software products that *should* work with SQL2025 when it is released currently playing catch-up? It has been 3 months since SQL2025 was released (18 Oct 2025).
I can understand why currently supported (i.e. not out of support, but in extended support) versions of Microsoft tools (think System Center) don’t work with the new SQL product. I am wondering about several vendors (think Idera, Cohesity, etc.) whose products don’t yet support SQL2025. Perhaps the ‘early access’ that vendors were allowed for this product wasn’t early enough for them to develop versions of their products.
It just seems like Microsoft testing and planning of/for their products is still an issue. Having 3rd part partners behind the curve on product support will only hinder adoption of the new SQL version.
Having an entire fuction (like Database Mail) fail in a CU deployment…shouldn’t occur with full regression testing. Testing with vendors appears to be late as well.
Don’t you love paying for the privilege of being a Microsoft Beta tester?
Can’t wait to see Brent teaching with the new SSMS Copilot autocompletion feature active… 😛
It looks like it is also caused by just the Hotfix: 4235 for Microsoft SQL Server Browser – KB5074819.
We auto-installed this Hotfix (without the Cumulative update) and it caused the issue. Removing it completely resolved the issue.
[…] SQL Server 2025 CU1 is Off to a Rough Start (Brent Ozar) […]
I asked my favourite LLM about this yesterday, and it told me SQL Server 2025 hasn’t RTM’d yet. It was completely unaware. Today I sent it a correction linking this URL and it was *very* grateful. AI isn’t all bad, I guess, and doesn’t want to be wrong! I know the feeling ….
This is just a test. Sorry Brent!!!
This is why i always wait 30 days before adopting any Sql CU. The risk is lower to live without the fixes then be an immediate adopter
Evergreen rule: test all updates before deploying to production.
Randolph – hey, I think you accidentally typed this into the wrong browser tab. I think you meant to type this into an internal Microsoft site advising your peers.
WINK WINK
WINK
WINK WINK WINK
(sprains facial muscles from winking)
That would require some sort of QA department to exist, and since Satya is allergic to QA people…
Zing
OMFG that would have driven me bonkers if I ran into that error ever as I’d have never figured it out was a bug that MS introduced in the CU.