Error: "Not a valid 32-bit application"

If you see the message “Not a valid 32-bit application” while installing the BigContacts Outlook Plugin, it means your system may not be compatible with the file you’re trying to run—or something is preventing it from installing correctly.

This is a common Windows error, especially on older systems like Windows 7 or when there's a mismatch between the version of Outlook, Windows, and the plugin installer.

Here’s what could be causing the issue—and how to troubleshoot it.

1. The file may be corrupted or incomplete

A damaged or incomplete download can cause this error. Here's what to do:

Re-download the plugin from the official BigContacts source.
Try saving it to a different folder or drive and running it again.
If your hard drive is showing other issues, run these system checks:

Run System File Checker (SFC)

Click Start, type CMD, then right-click Command Prompt and select Run as Administrator
Type: sfc /scannow
Press Enter
Wait for the scan to complete and restart your system

Run Check Disk (CHKDSK)

Open Command Prompt as Administrator again
Type: chkdsk /r /f
Press Enter
Restart your computer to allow the scan to run

These tools check and fix system file or hard drive issues that may affect installations.

2. The file isn't compatible with your version of Windows

You may get this error if:

You're trying to install the 64-bit plugin on a 32-bit version of Windows
You're using an unsupported version of Outlook

BigContacts Plugin Compatibility

Supported Windows Versions

Windows XP (32-bit)
Windows Vista (32-bit)
Windows 7 (32-bit or 64-bit)
Windows 8 (32-bit or 64-bit)

Supported Outlook Versions

Outlook 2007
Outlook 2010 (32-bit or 64-bit)
Outlook 2013 (32-bit)
Office 365 (installed desktop version of Outlook only)

Not supported: Mac systems or the web-based version of Office 365 Outlook.

If your setup doesn’t match these requirements, the plugin may not install. If you're unsure about your Outlook version, go to File > Office Account > About Outlook to check if it's 32-bit or 64-bit.

3. Your antivirus or another program is blocking the installation

In some cases, antivirus software or other background processes can interfere with installations.

Try this:

Restart your computer in Safe Mode
Attempt to run the installer again
If it works in Safe Mode, something running in the background (like antivirus or firewall software) may be blocking the process

If you're unsure how to enter Safe Mode, here's a quick Microsoft guide:
Start your PC in Safe Mode

Final Notes & Known Plugin Limitations

Some Outlook installations in Australia may have timezone syncing issues with daylight savings. For example, a 4:15 pm meeting in BigContacts may appear as 5:15 pm in Outlook.
This error can often be solved by confirming compatibility first—especially between 32-bit and 64-bit systems.

Still stuck?

If you're not sure whether your system meets the requirements or you're still seeing errors, contact our team at support@bigcontacts.com. We'll help you get the right version and guide you through installation.