This error in Turbotax software is caused by misconfigured system files in your Windows operating system. There can be many factors responsible for this error. Like there is incomplete installation, spyware attack. Improper deletion of applications or hardware. You can fix Turbotax error code 65535 by the following steps –

• Scan the computer with a repair tool
• Close the error window and try to reinstall
• Restart the device and then launch Turbotax
• Repair registry entries associated with the error
• Uninstall and reinstall the software