To fix this error in HandiTax, app failed to start because the side-by-side configuration is incorrect.
Close the HandiTax year affected.
Open File Explorer and navigate to the HSoft\Apps Folder.
Rename the HtXX.exe.Config file (or for SQL: HtXXSql.exe.Config) to HtXX.exe.ConfigOLD.
xx represents the year of HandiTax e.g, HT22.exe.configOLD.
Re-open HandiTax. This will generate a new config file, and the error should be resolved.