HubSpot Sales for Outlook install error: 'Application cannot be started. Contact the application vendor.' Last updated: January 17, 2023 Applies to: All products and plans You may encounter the following error messages when attempting to install the HubSpot Sales Outlook desktop add-in: Application cannot be started. Contact the application vendor. To resolve this error: Uninstall the HubSpot Sales Outlook desktop add-in. Press CTRL + ALT + DEL and open Task Manager, then end the SidekickTrayWPF.exe process. Navigate to Control Panel and select Uninstall a program or Add or remove programs. Search for and uninstall HubSpot Sales for Windows. Install the HubSpot Sales for Windows tray app. connected email