In most cases, this error is caused by interference from antivirus, antimalware, or firewall programs, or from a backup program interfering with the Windows installer. It can also occur if there is not enough free space on the Windows drive or if the user is not logged in as an administrator. Other potential causes of Error 1603 include a severely outdated Windows build, a proxy/VPN interference, and a missing .NET dependency. If you are experiencing this issue with TurboTax, follow the steps provided below to troubleshoot and resolve Error 1603.
1. Update Windows to the latest version
The primary cause of the 1603 error with TurboTax is typically an outdated version of Windows. TurboTax requires the latest feature update available for Windows 10 or Windows 11 in order to meet security protocols. If you have been postponing updates and encounter the 1603 error when trying to update the TurboTax app, installing all pending Windows updates should resolve the issue. To update your Windows build, follow these instructions: Here’s how to update your Windows build:
2. Use an administrator account
One solution that has been known to help some TurboTax users is to run the executable on an admin account. If you are logged in with an administrator account, you will have access to every aspect of Windows. If you do not currently have an administrator account to use, the steps below will guide you on how to convert a standard Windows account into an administrator account:
3. Disable antivirus, antimalware, or firewall
Another possible cause of the 1603 error when updating TurboTax is interference from antivirus, antimalware, or firewall software. Some users have reported that third-party security suites can cause this issue, but Windows Security (Windows Defender + Windows Firewall) can also be the culprit. If you are using a third-party security suite, temporarily uninstalling it before attempting to update TurboTax can resolve the issue. You can use this guide to ensure that no remnant files are interfering with the update process. If you are using Windows Firewall and Windows Security’s real-time protection, you can resolve this issue by disabling the Windows Firewall and Real-time Protection. Here’s a quick guide on how to disable the Windows Firewall and Real-time Protection to prevent interference:
4. Install missing .NET framework dependencies
Since TurboTax was originally built for Windows 7, you might have quite a few missing dependencies if you’re on Windows 11 and you didn’t install any .NET framework packages manually. Fortunately, you can resolve this issue easily by running a DISM command from a compatible Windows installation media. Here’s a quick guide on how to do this:
5. Disable VPN or Proxy server
You can also expect to see the 1603 error when updating TurboTax if the authentication module is inhibited by a proxy or VPN program. TurboTax, like most other income tax return apps, is known to malfunction when used on a proxy or VPN server. If you use your device both at home and at the office, it is important to stop the proxy connection or delete the VPN module before retrying the update. The required steps may differ depending on whether you are using a proxy or a VPN. We’ve two sub-guides to assist you with disabling VPN and proxy connections. Follow the instructions that apply to your specific situation:
Disable VPN Connection
If you established your VPN connection using the VPN connection tab, you can only disable this functionality via the Network & Internet Connections menu. The steps necessary to deactivate a native VPN connection on Windows are as follows:
Disable the Proxy Connection
To disconnect the proxy connection and prevent interference with the updating process of TurboTax, you must browse to the Settings menu and disable the active proxy from the Proxy tab. Inside, you will be able to determine whether the proxy server is operational and, if required, shut it down to prevent it from interfering with TurboTax. Here’s how to do this:
