To resolve this issue:
Exit out of all HandiSoft programs.
Go to File Explorer on the server drive.
Go to HSoft\Apps.
Scroll down the Type column and under the Type, Application, locate and double-click the HandiTax program with the issue. For example, if it is HandiTax 2025 then you will locate Ht25.exe.
Locate and select the client you require.
If no further error arises, you can continue working in HandiTax as it is the correct database.