Recently, I upgraded LocalDB from version 13 to 14 using the SQL Server Express installer and this instruction. After the installation, I stopped the existing default instance (MSSQLLOCALDB) of version 13 and created a new one, which automatically used the v14.0.1000 server engine.

I often use LocalDB for Database Integration tests, i.e. in my xunit tests, I create a (temporary) database which is deleted when the test finishes. Since the new version, unfortunately all my tests fail because of the following error message:

CREATE FILE encountered operating system error 5(Access is denied.) while attempting to open or create the physical file 'C:\Users\kepflDBd0811493e18b46febf980ffb8029482a.mdf'

The odd thing is that the target path for the mdf file is incorrect, a backslash is missing between C:\Users\kepfl and DBd0811493e18b46febf980ffb8029482a.mdf (which is the random database name for a single test). The databases are created via the simple command CREATE DATABASE [databaseName] - nothing special here.

In SSMS, I see that the target locations for data, log, and backup are the following:

However, when I try to update the location, I get another error message:

How can I update the default locations so that LocalDB is able to create databases again? It's obvious that LocalDB does not correctly combine the default location directory and the database file name - is there a registry entry that I can edit? Or anything else?

Recently, I upgraded LocalDB from version 13 to 14 using the SQL Server Express installer and this instruction. After the installation, I stopped the existing default instance (MSSQLLOCALDB) of version 13 and created a new one, which automatically used the v14.0.1000 server engine.

I often use LocalDB for Database Integration tests, i.e. in my xunit tests, I create a (temporary) database which is deleted when the test finishes. Since the new version, unfortunately all my tests fail because of the following error message:

CREATE FILE encountered operating system error 5(Access is denied.) while attempting to open or create the physical file 'C:\Users\kepflDBd0811493e18b46febf980ffb8029482a.mdf'

The odd thing is that the target path for the mdf file is incorrect, a backslash is missing between C:\Users\kepfl and DBd0811493e18b46febf980ffb8029482a.mdf (which is the random database name for a single test). The databases are created via the simple command CREATE DATABASE [databaseName] - nothing special here.

In SSMS, I see that the target locations for data, log, and backup are the following:

However, when I try to update the location, I get another error message:

How can I update the default locations so that LocalDB is able to create databases again? It's obvious that LocalDB does not correctly combine the default location directory and the database file name - is there a registry entry that I can edit? Or anything else?

Update after Doug's answer and sepupic's comment

According to this Stackoverflow question, the default location's should also be changeable via the registry. However, if I try to find the corresponding keys "DefaultData", "DefaultLog" and "BackupDirectory", I cannot find them in my registry. Did SQL Server v14 rename these registry keys, or moved these information out of the registry?