When lodging a tax return in HandiTax the 'cannot open, unknown error' error may occur.
Exclude the HSoft folder from real-time antivirus scanning
Open your antivirus program.
Locate the settings for real-time protection or exclusions.
Add the HSoft folder to the exclusion list.
Update ELS Folder Path in HandiTax SQL
Open HandiTax SQL version.
Go to Options, ELS Communication Options.
Click the ellipsis (...) next to the ELS Folder path.
Reselect the correct ELS folder (typically within the HSoft directory).
Click OK to save the changes.