"An attempt was made to load a program with an incorrect format" error when deploying to WP8 RRS feed

  • Question

  • I have a WP7.1 project that i can't deploy to WP8 (Emulator or Device). When i do i get the following error.

    So far i have tried

    • Converting to a WP8 app but had no luck (i rolled this change back)
    • Upgrading VS2012 to update 2
    • Installed Windows Phone 7.8 SDK
    • Deploying to a WP7 VM - This works 
    • Deploying to a WP8 VM - Fails with this error but the OS loads
    • Deploying to a WP7 device - This works
    • Deploying to a WP8 device - Failes with this error
    • Created a new 7.1 project and manually copied all classes and third part dll's - Still fails with this error

    more details of what i have tried so far are on my stackoverflow question


    As you can see the error is not very helpful to locate the cause of the problem. Can anyone suggest something to help narrow down the problem?

    • Edited by Nitro52 Friday, April 19, 2013 9:29 AM
    Friday, April 19, 2013 9:28 AM

All replies

  • Hi,

    After converting the app to a WP8 app, have you tried deleting and then re-adding all the References, to ensure your app uses the newer libraries? Also Clean the project and make sure there are no stray DLLs in your solution, before recompiling?


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    Monday, April 22, 2013 4:30 PM
  • Hi, 

    I have the same error and i made many trials and the error still happens . Do you solve this error ?

    Thanks a lot :)

    Nada Gamal 

    Saturday, October 12, 2013 10:25 AM
  • Any Solution for this problem 


    Wednesday, May 7, 2014 2:57 PM
  • This error happens when your app targets the wrong CPU type. For example, if you target x86 but you have a 64-bit CPU.

    You can fix it by following the following steps:

    • Open project properties window
    • Select Build tab
    • Change it to ‘Any CPU’
    • Save your changes.
    • Compile your project and run :)

    Hope this helps!

    Paras Wadehra
    Microsoft MVP
    Microsoft Developer Ambassador
    INETA Community Champion

    Paras Wadehra Twitter: @ParasWadehra (Nokia Developer Ambassador)

    • Proposed as answer by ParasWadehra Thursday, May 8, 2014 4:12 AM
    Thursday, May 8, 2014 4:11 AM
  • All my projects olny have one option, "Any CPU". i guess it could be a dependency dll i am referencing but how can you tell what CPU type a dll targets?
    Thursday, May 8, 2014 10:50 AM