Please start by reinstalling the application.

If this does not help, proceed further.

In Windows, MS SQL integrates with the OS deeply, and it may be difficult to change the situation if something went wrong.

So we have to resort to radical measures. Some customers report that they could restore the proper MS SQL operability only after re-installing the OS completely.

Before reinstalling the OS, however, please try this:


SQL Server tools and many older installers expect computer names of 15 characters or less (Windows NetBIOS limit). When the installer tries to build a connection string with the full long name, it can silently truncate or fail string operations and then report the generic "Unable to fix MSSQLLocalDb instance" message. So the solution might be to rename the computer to a short name:
 - Press Win + I to open Settings.
 - Go to System, then About.
 - Click "Rename this PC".
 - Choose a short name without spaces or special characters, max 15 characters.
 - Restart the computer when prompted.

After restart, please open Command Prompt as administrator and run:
sqllocaldb stop "MSSQLLocalDB"
sqllocaldb delete "MSSQLLocalDB"
sqllocaldb create "MSSQLLocalDB"
sqllocaldb start "MSSQLLocalDB"
sqllocaldb info "MSSQLLocalDB"
The last command should show State: Running. Then right-click the TO3000 5D installer and choose "Run as administrator". 

Next thing to try: 

Install MS SQL Server 2022 Express manually - get it here: https://www.microsoft.com/en-us/download/details.aspx?id=104781

Use the Basic option during the installation.

Then install TO3000 again with the Demo or Empty database option.

If MS SQL 2022 fails to install:

Please try to change the sector size of your hard drive using the process described here:
https://learn.microsoft.com/en-us/troubleshoot/sql/database-engine/database-file-operations/troubleshoot-os-4kb-disk-sector-size?tabs=registry-editor#resolution-steps-for-disk-sector-size-errors-in-sql-server :

1. Run Registry Editor as an administrator.
2. Navigate to Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\stornvme\Parameters\Device.
3. Select Edit > New > Multi-String value and name it as ForcedPhysicalSectorSizeInBytes.
4. Right-click the name, select Modify, and type * 4095 in the Value data field.
5. Select OK and close Registry Editor.
6. Re-start your computer.

Then please try reinstalling TO3000.

If this does not help:

Note: The below actions are likely to interrupt all SQL-related apps on your computer.

For example, MemoQ uses MS SQL as well. These may also affect older versions of TO3000 operation.
So make all necessary backups and proceed with caution.

0. Uninstall all versions of TO3000 (3D and later)

1. Open Settings
- Press Win + I or click Start → Settings

2. Go to Apps
- Click Apps in the left sidebar
- Select Installed apps

3. Search for SQL apps
- In the search bar at the top, type SQL
- This will filter and show only apps with "SQL" in the name

4. Uninstall each app
- Click the three dots (⋯) next to each app
- Select Uninstall
- Follow the on-screen prompts

5. Repeat for all SQL-related apps in the list

Then physically delete MS SQL folders from your computer.

The default locations to purge are:
"C:\Program Files (x86)\Microsoft SQL Server\120"
"C:\Program Files (x86)\Microsoft SQL Server\160"
"C:\Program Files\Microsoft SQL Server\120"
"C:\Program Files\Microsoft SQL Server\160"
"C:\Users\Public\Documents\AIT\TO3000, Version 5D"
"C:\Users\Public\Documents\AIT\TO3000, Version 3D"
"C:\Users\Public\Documents\AIT\TO3000, Version 3D+"

After that, please restart your computer and install TO3000 again - with the Empty database option - and restore your database from backup in TO3000.