Could not load file or assembly ... An attempt was made to load a program with an incorrect format (System.BadImageFormatException)
Solution 1:
I am pretty sure you're having a 32-bit / 64-bit conflict. It sounds like your main project might be set to 32-bit while the class its referencing is set to 64-bit. Try looking at this SO question and this one too. Between the two of them, you should be able to figure out your problem.
Solution 2:
Might be you are facing the problem with your website after deploying on server.
Then you need to adjust your application pool to Enable 32-Bit Applications.
Steps
- Open IIS Manager
- Click on Application Pools
- Select whatever application pool you are using
From right pane, click Advanced Settings...
-
Set Enable 32-Bit Applications to True
Solution 3:
I just had this error message running IIS Express in Visual Studio 2015. In my case I needed to be running the 64 bit version of IIS Express:
Tools → Options → Projects and Solutions → Web Projects
Check the box that says "Use the 64 bit version of IIS Express for web sites and projects".
Screenshot:
Solution 4:
I had this same problem. I had set Project A's "Platform Target" ("Project A"(Right Click)->Properties->Build->"Platform Target") to x86 but kept Project B's at "Any CPU". Setting Project B's to "x86" fixed this.
Solution 5:
I had this problem running unit tests (xunit) in Visual Studio 2015 and came across the following fix:
Menu Bar -> Test -> Test Settings -> Default Processor Architecture -> X64