Fix ‘An attempt was made to load a program with an incorrect format’

Madalina Dinita
by Madalina Dinita
Former Managing Editor
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  • Some programs were specifically designed for a 32-bit system. Incompatibilities with 64-bit operating system might appear even though they are quite rare now.
  • This issue showed when using Start Menu replacements. Remove them to get rid of the issue. For Visual Studio users there's a setting found in the article that you need to do.
  • The article is part of the System Errors series that you can bookmark for future reference in case of similar errors.
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error bad format

If you’re getting the ERROR_BAD_FORMAT error code 11 with the An attempt was made to load a program with an incorrect format description, follow the troubleshooting steps listed in this article to fix it.


The error An attempt was made to load a program with an incorrect format is quite a mysterious error code. There is not much information about it, except for various forum posts where users describe the problem.

The ERROR_BAD_FORMAT error code affects mainly Windows 7 machines, but sometimes it can also occur on Windows 10. It usually occurs when users try to launch an app or program on their Windows PCs or servers.

Error code 11 is often triggered by VS Redistributable package issues, incompatibility problems between programs, incorrect registry changes, etc.

How to fix error 10: ERROR_BAD_FORMAT

ERROR_BAD_FORMAT on .NET platforms

Solution 1 — Enable 32-bit compatibility

Users report that this error mainly occurs due to DLL incompatibility issues triggered by apps running in Visual Studio installed on 64-bit operating systems with the value TargetCPU = Any CPU. In other words, apps try to load DLLs built for 32-bit platforms on x64 computers, and vice versa.

To fix this problem, you need to configure the utility to run as a 32-bit .NET process using CORFLAGS.

  1. Download CORFLAGS from Microsoft’s Support page
  2. Run it as follows to switch the 32-bit execution mode on: corflags utility.exe /32Bit+
  3. Use /32Bit- in the above command line to turn it off.

You can also enable 32-bit compatibility in the Windows form application. Simply right-click on Project > go to Properties > Build > check Prefer 32-bit.

Additionally, you can also use the Any CPU option, and use a dedicated code to identify which DLL to use. In this manner, you will use one assembly to handle both 32-bit and 64-bit platforms. Here is the code to use:

if (Environment.Is64BitProcess)
//call MiniDumpWriteDump
//call MiniDumpWriteDumpX86

You can also use preprocessor conditions, but in this case you need to compile two different assemblies. In other words, compile a 32-bit assembly for 32-bit platforms, and a separate 64-bit assembly for 64-bit platforms.

Solution 2 — Install the correct VS Redistributable Package

Your target PC might not have the appropriate VS Redistributable Package installed. Go to Microsoft’s webpage and install the appropriate VS Redistributable Package version on your system.

Fix ERROR_BAD_FORMAT on Windows 10

On Windows 10, the An attempt was made to load a program with an incorrect format error usually occurs on startup and is due to software incompatibility issues. Users confirm that this problem often occurs when using Start Menu replacement tools.

If you’re using a Windows 10 Start menu replacement, uninstall it and that should do the trick.

Also, don’t forget to repair your registry. The simplest way to repair your registry is to use a dedicated tool, such as CCleaner. Don’t forget to first backup your registry in case anything goes wrong. If you haven’t installed any registry cleaner on your computer, check out our article on the best registry cleaners to use on Windows 10 PCs.

You can also use Microsoft’s System File Checker to check for system file corruption. Here’s how to run an SFC scan:

1. Go to Start > type cmd > right-click Command Prompt > select Run as Administrator

2. Now type the sfc /scannow command

3. Wait for the scanning process to complete and then restart your computer. All corrupted files will be replaced on reboot.

We hope that the solutions listed above helped you fix the  ERROR_BAD_FORMAT error code 11. As always, if you’ve come across other solutions to fix this problem, you can list the troubleshooting steps in the comments below.

FAQ: Learn more about ERROR_BAD_FORMAT


It is usually an error message useful for debugging an application that is being developed. Most of the times, it applies to incompatibilities between 32-bit and 64-bit software version and the operating system.

  • What can I do to fix ERROR_BAD_FORMAT?

As a user, uninstall any Start Menu replacements. As a developer, see the solutions in this article for more details.

Editor’s Note: This post was originally published in September 2017 and has been since revamped and updated in May 2020 for freshness, accuracy, and comprehensiveness.