SQL Server 2025 CU1 arrives… and gets pulled because it breaks database mail

What is (was!) in CU1

CU1 addressed the following issues:

Reliability fixes

• DBCC CHECKDB could hang in rare situations with computed columns

• Resource Governor trace flag combinations that could hang servers were fixed

• Stack dumps require sysadmin privileges, so you don’t accidentally expose sensitive info

Tools and connectivity

• SQLCMD crashing when using -N in :CONNECT commands was fixed

• SQL Server Configuration Manager no longer hangs on certificate import

Linux-specific fixes

• CPU metrics in DMVs now report correctly

• Active Directory login handling is smoother when passwords rotate or keytabs change

• Linux container support was improved

• Daylight saving time issues in time zone functions were corrected

Full-text search

• .docx files that start paragraphs with hyperlinks now index properly

Why did it get pulled?

Microsoft quickly pulled the update as it broke database mail. Oops.

So you are most likely to encounter this issue if:

• You are running SQL Server 2025 with Cumulative Update 1 applied
• Database Mail is enabled and actively used
• Email notifications are part of operational or business-critical workflows

After applying CU1, Database Mail may fail to send messages. Jobs that depend on DBMail might not complete successfully, and alerts that normally notify teams of failures may never be delivered. Microsoft has acknowledged the issue in the CU1 release notes.

If you have installed it and Database Mail is broken, roll back the update as per Microsoft’s instructions.

Hot take: not such a bad thing

Friendly reminder: if you’re using Database Mail… you (probably) shouldn’t be using Database Mail.

DBMail is a relic from a time when there was no other way to get alerts or notifications out of your environment. It was intended to help DBAs monitor environments and raise issues as they arose and not much else. But as typically happens with these sorts of ‘features’ they get converted for use in all sorts of unintended ways.

Today there are far better ways to send business domain notifications from your application.

But if you insist on using it, keep your eyes peeled for Microsoft’s updated release once the Database Mail issue is resolved.