SQL Server 2025 LocalDb installation is missing components

According to https://learn.microsoft.com/en-us/sql/sql-server/editions-and-components-of-sql-server-2025 - "SQL Server Express LocalDB is a lightweight version of Express edition that has all its programmability features"

Therefore I would expect to be able to use SQL Server 2025 features such as REGEXP functions and the vector column type. But using either of these features causes the SQL LocalDb process (C:\Program Files\Microsoft SQL Server\170\LocalDB\Binn\sqlservr.exe) to crash.

For example - connect to a LocalDB instance and execute a simple regexp_replace:

C:\>sqllocaldb start mssqllocaldb
LocalDB instance "MSSQLLocalDb" started.

C:\>sqllocaldb info mssqllocaldb
Name:               MSSQLLocalDb
Version:            17.0.1000.7
Shared name:
Owner:              MY-PC\MyUser
Auto-create:        Yes
State:              Running
Last start time:    09/12/2025 2:52:37 PM
Instance pipe name: np:\\.\pipe\LOCALDB#BAE68F2C\tsql\query

C:\>sqlcmd -S "np:\\.\pipe\LOCALDB#BAE68F2C\tsql\query"

1> select @@version
2> go
------------------------------------------------------------------------------
Microsoft SQL Server 2025 (RTM) - 17.0.1000.7 (X64)
        Oct 21 2025 12:05:57
        Copyright (C) 2025 Microsoft Corporation
        Express Edition (64-bit) on Windows 10 Pro 10.0 <X64> (Build 26200: )
(1 rows affected)

1> select regexp_replace('the cat sat on the mat','cat','dog')
2> go
Named Pipes Provider: The pipe has been ended.
Communication link failure

In the C:\Users\username\AppData\Local\Microsoft\Microsoft SQL Server Local DB\Instances\MSSQLLocalDb\error.log is the following:

2025-12-09 15:02:52.91 spid78      *
2025-12-09 15:02:52.91 spid78      * BEGIN STACK DUMP:
2025-12-09 15:02:52.91 spid78      *   12/09/25 15:02:52 spid 78
2025-12-09 15:02:52.91 spid78      *
2025-12-09 15:02:52.91 spid78      *
2025-12-09 15:02:52.91 spid78      *   Exception Address = <frame id="00" address="0x7FFA5DF380DA" pdb="kernelbase.pdb" age="1" guid="8314490F-9967-05E2-CF4A-8DF59DF277DB" module="kernelbase" rva="0xC80DA" />
2025-12-09 15:02:52.91 spid78      *   Exception Code    = c06d007e EXCEPTION_MOD_NOT_FOUND
2025-12-09 15:02:52.91 spid78      *   Delay load failure occurred for module 'RegExpr.dll' (Error: The specified module could not be found.)
2025-12-09 15:02:52.91 spid78      * Input Buffer 144 bytes -
2025-12-09 15:02:52.91 spid78      *             select regexp_replace('the cat sat on the mat','cat','dog')  
2025-12-09 15:02:52.91 spid78      *  

That shows RegExpr.dll is missing.

If you copy RegExpr.dll from a SQL Express install (e.g.
from C:\Program Files\Microsoft SQL Server*MSSQL17.MSSQLSERVER\MSSQL\Binn*
to C:\Program Files\Microsoft SQL Server*170\LocalDB\Binn*) - it works!

Similar issue if you try to define a column as the vector type - it crashes complaining vectorffi.dll is missing - copying it across fixes the issue.

This has been reproduced on a number of machines so appears to be an issue with SQLLOCALDB.MSI missing the correct files.