I need to restore a backup for an assignment, but SMSS said I was running v13 while the backup was made in v15. So I downloaded and installed SQL Server Express 2019 and uninstalled the older version.

However, SMSS can't connect anymore to (localdb)\MSSQLLocalDB.

I read somewhere to add a firewall rule for sqlservr.exe. When I try to run that file manually, it says the SQL Server installation is corrupt.

So I ran the Repair from SQL Server Installation Center, everything was okay in the output log but still no luck. I'm pretty clueless, any help is appreciated.

The available services:

Status Name DisplayName
Stopped SQLAgent$SQLEXP... SQL Server Agent (SQLEXPRESS)
Stopped SQLBrowser SQL Server Browser
Running SQLWriter SQL Server VSS Writer

The list of LocalDb instances:

PS C:\Program Files\Microsoft SQL Server\150\Tools\Binn> SqlLocalDb.exe i

PS C:\Program Files\Microsoft SQL Server\150\Tools\Binn> SqlLocalDb.exe s "MSSQLLocalDB"
Start of LocalDB instance "MSSQLLocalDB" failed because of the following error:
Cannot create an automatic instance. See the Windows Application event log for error details.

Event viewer details:

LocalDB parent instance version is invalid: MSSQL13E.LOCALDB


2 Answers 2


LocalDB parent instance version is invalid: MSSQL13E.LOCALDB

This is cause by an incorrect registry setting. It can be fixed manually, but it is easier and less dangerous to delete and recreate the instance from a command prompt:

sqllocaldb stop MSSQLLocalDB
sqllocaldb delete MSSQLLocalDB
sqllocaldb create MSSQLLocalDB

There are details about registry editing on Stack Overflow if you prefer to go that route.


check the

SQL Server Configuration Manager see manual

enter image description here

On the right side you see which server are running and how to call them in the brackets.

and see if it is called MSSQLLocalDB any longer

  • Ok, so SQLEXPRESS is accessible as before, but I would need/like to use localdb/MSSQLLocalDB
    – FDM
    Feb 28, 2021 at 20:48
  • then you have to add a new instance with that name and copy all data
    – nbk
    Feb 28, 2021 at 21:24

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