The blog of Windows Wally, a Windows Support Technician helping common people solve frustrating computer problems.



How to Fix the “not a valid Win32 application” Error

Reader Question:
“Hi Wally, When I try to start the messenger an error appears saying it is not a valid win 32 application!”   - Brittany S., USA

Before addressing any computer issue, I always recommend scanning and repairing any underlying problems affecting your PC health and performance:

  • Step 1 : Download PC Repair & Optimizer Tool (WinThruster for Win7, XP, Vista – Microsoft Gold Certified).
  • Step 2 : Click “Start Scan” to find Windows registry issues that could be causing PC problems.
  • Step 3 : Click “Repair All” to fix all issues.

Setting up weekly (or daily) automatic scans will help prevent system problems and keep your PC running fast and trouble-free.

Wally’s Answer: This error occurs for various reasons. If your messenger software worked beforehand, then it could be due to a virus or malware. If you just installed the messenger then it might not be compatible with your version of Windows. Win32 errors can occur for various reasons.

Win32 Programs or Applications

Win32 applications are 32-bit applications that conform to the rules of the Win32 API. So, basically its a standard format for applications that run on 32-bit Windows. Win32 applications can take advantage of multiple processors. All Win32 application have a .exe extension.

General Causes of Win32 Errors

  1. Program was designed for a different version of Windows.
  2. One of the program’s files was deleted somehow.
  3. One of the program’s files became corrupt.
  4. Virus or malware infection.
  5. Incompatibility issues.

Win32 error due to Missing files

If you installed a program and later one of its files got deleted by accident, then the win32 error can occur. Try reinstalling the software, maybe this time, download the setup file from another source.

File is not designed for your version of Windows

If you have a new version of Windows installed on your computer and you are trying to run a program that was designed for older versions of Windows then, you may get this error. This is rare, since most old programs still run on newer versions of Windows.

You can try running it in Compatibility Mode

Right-click the program and click Properties
Win32 - right-click - Properties - WindowsWally

Click Compatibility tab > under Compatibility mode, check Run this program in compatibility mode for: and select the desired operating system > click OK
Win32 - right-click - Properties - Compatibility Mode - WindowsWally
Some very old programs might require you to check the Run in 640X480 checkbox as well. This will not work for most MS-DOS programs. For them you will need to use an MS-DOS emulator like DosBox.

Win32 error caused by Uninstalled software

You may be trying to run a software that is no longer installed on your computer. Verify whether it is still installed by opening the Add or Remove programs menu, and looking for your program there.

Click the Start button > type Add or Remove Programs > press Enter (look for the program you are trying to run, is it in the list?)
Add or Remove Programs

Win32 errors due to Bad Sectors

This is rare, but your hard drive might have bad sectors. You can run a hard drive diagnostics test from your BIOS to determine the health status for your computer’s hard drive. If your computer’s hard drive does not pass the diagnostics test then you will need to replace it. Restart your computer and look for text on your screen saying Diagnostics test, Options, or Settings. Refer to your computer’s manual if you need to. This is a hardware problem, and for most modern computers it means that you have to backup and replace the hard drive to prevent the risk of losing your important data.

32 and 64 bit version

Windows comes in 32-bit and 64-bit versions. The 32-bit version cannot run 64-bit applications but the 64-bit version can run 32-bit applications just fine. Trying to run a 64-bit application on 32-bit version of Windows can cause the win32 error to appear. You can check whether your copy of Windows is 32 or 64 bit.

Click Start > click Computer > right-click an empty space > click Properties, look under System, System TypeWin32 - computer - right-click - Properties - WindowsWally

Virus or Malware infection

With modern operating systems like WIndows 7 and Windows 8, the odds of a virus infection are slim. Although if your computer does get infected with a virus, it can attach itself to executable files, and thus the win32 error might appear if you try to run it. Try scanning your computer with an anti-virus software. It is more likely that your computer might be infected with malware, use a reliable anti-malware software.

Is Your PC Healthy?

I always recommend to my readers to regularly use a trusted registry cleaner and optimizer such as WinThruster or CCleaner. Many problems that you encounter can be attributed to a corrupt and bloated registry.

Happy Computing! :)

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About the Author

Windows Wally is a helpful guy. It’s just in his nature. It’s why he started a blog in the first place. He heard over and over how hard it was to find simple, plain-English solutions to Windows troubleshooting problems on the Internet. Enter: Windows Wally. Ask away, and he will answer.