Known Issue: "Unable to Download" Error During In-App Upgrade

When attempting to perform an in-app upgrade, users may encounter an "Unable to Download" error that prevents the upgrade from completing. 

Root Cause 

The error occurs when the user account running Cerberus FTP Server does not have write permissions to the installers directory: 

C:\ProgramData\Cerberus LLC\Cerberus FTP Server\installers 

During an in-app upgrade, Cerberus downloads the installer package to this directory. If the current user lacks write access, the download fails and the error is displayed. 

Workarounds

Option 1 - Run the upgrade as an Administrator

Log in to Windows as an administrator (or use an account with administrative privileges), then retry the in-app upgrade from within Cerberus. 

Option 2 - Grant write access to the installers folder 

Manually grant the user account running Cerberus write permissions to the following directory:

 C:\ProgramData\Cerberus LLC\Cerberus FTP Server\installers 

Once permissions are updated, retry the in-app upgrade. 

Notes 

• This issue is most commonly seen in environments where Cerberus runs under a restricted or service account. 
•  If neither workaround is suitable, the upgrade can also be performed manually by downloading the installer directly from the Cerberus website and running it as an administrator.