Adobe Flash Builder and the Application Descriptor File


This is one of the easiest fixes ever, but I believe I’m the first on the internet to blog about this issue. The issue arises when building a mobile project in Adobe Flash Builder with the Air namespace. In the *-app.xml file, the namespace is what is used to define whether the XML document is “well-formed” or not.

If your [project]-app.xml file is generating a namespace error, it could be one of two things. The first is simply that the namespace version is not up-to-date. In this case, the “problems” panel will show you which version you should be using.

If it’s saying your version is 0.0.0 and you know you have 3.1 or 3.2 in the namespace, then you probably have the same issue. Here’s the error message:

namespace 0.0 in the application descriptor file should be equal or higher than the minimum version 3.1 required by flex sdk

If this issue comes up, your problem might be as simple as directional quotes. This could happen if you have typed ‟ or ” rather than “. The solution is simple. Make sure that your quotation marks are not directional. Here’s how your namespace declaration should look.

<application xmlns=”″>

Hope that was helpful for you.

6 thoughts on "Adobe Flash Builder and the Application Descriptor File"

  1. chima says:


    I have encountered the same issue on Flash Builder 4.6.
    The error message was completely the same as yours, but the case looks different.

    In my case, the error occurs every time when I try to launch (build-run at once) a FlexUnit4 test application,
    and, I believe, only when the application’s parent project has a connection with my local SVN repository (by Subclipse).

    I am not sure about the detail, but my solution was also simple
    – Build the project and then run (not at once).


    My namespace declaration of an application descriptor is always as follows. Its quotation marks are “(ASCII-0x22).

  2. Vipul says:


    I have encountered the same issue on Flash Builder 4.6.
    The error message was completely the same as yours
    Can you tell me what to do.

  3. Vipul says:

    I have included the same

    but still its throwing same error.

  4. jsandahl says:

    Did you try changing out your quotation marks? The other thing you might try is uploading the xml file and running on it.

  5. Ram Iyer says:

    Ok, the last post converted the ampersand code… check for & copy ; (without the spaces) or any other such codes and remove them…

  6. Nick G says:

    using a validator I found that is was an extra blank line at the top of the code. smh.

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