Downloading and installing Flex 4 SDK builds from (Flash Builder 4 beta Edition)

In a previous example, “Downloading and installing Flex SDK builds from”, we saw how to install a nightly build of the Flex SDK from and install it into Flex Builder 3.

The following example shows how you can download and install a nightly build of the Flex 4 SDK into Flash Builder 4 (formerly Flex Builder).

Downloading and installing Flex 4 SDK builds into Flash Builder 4 (formerly Flex Builder)

  • To download the Flex 4 SDK, navigate to the following URL:
  • Download the latest nightly build. You can download either of the available SDK types (Adobe Flex SDK, Open Source Flex SDK, or Adobe Add-ons — see the “Downloading and installing Flex SDK builds from” for explanations between the different types). For this example I am downloading the latest nightly build of the Adobe Flex SDK (currently
  • Save the nightly build to your hard drive and extract the files from the .ZIP file.
  • In Flash Builder 4, select Window > Preferences from the main menu to open the Flash Builder Preferences dialog box. To add, edit, or remove a Flex SDK, select Flash Builder > Installed Flex SDKs.
  • Click the Add button to launch the Add Flex SDK dialog box and click the Browse button to navigate to the directory where you extracted the nightly SDK build in a previous step.
  • Click OK to apply your changes and add the new Flex SDK. If you want to set the newly downloaded SDK as your default SDK, click the check box to the left of the SDK name. Click OK to dismiss this dialog.

Q: I get an “unable to open ‘…/frameworks/libs/netmon.swc'” error after changing my Flex SDK.
A: If you are trying to use a nightly build with the Flash Builder 4 beta from Adobe Labs, you’ll likely get this error. Currently you’ll either need to disable network monitor for the current Flex project, or else copy an existing netmon.swc into your new SDK.

(a) Disabling network monitor:

  • In Flash Builder 4, select your Flex project and select Project > Properties from the main menu to open the project properties dialog box.
  • Select Flex Compiler from the left menu, and then deselect the “Enable network monitor” checkbox in the Compiler options area.
  • Click OK to apply changes and dismiss this dialog box.

(b) Copying netmon.swc from an older Flex SDK:

If you want to use the network monitor with a newer, nightly build of the Flex 4 SDK, you can copy the netmon.swc from the Flex SDK that shipped with the Flash Builder 4 beta.

  • Launch Windows Explorer or Mac Finder app and navigate to your Adobe Flash Builder 4 application folder. On Windows Vista, the SWC would be found at C:\Program Files (x86)\Adobe\Adobe Flash Builder Beta\sdks\4.0.0\frameworks\libs\netmon.swc.
  • Copy that netmon.swc into your nightly build’s /frameworks/libs/ folder.

The network monitor issue has been fixed in newer (internal) versions of Flash Builder 4, so these steps will no longer be needed in future drops of Builder. For more information, see

Q: I get a “An internal build error has occurred. Right-click for more information.” compiler error after changing my Flex SDK.
A: Most likely you’ll need to close Flash Builder 4 beta and relaunch it to remove this error. This has also been fixed in newer (internal) versions of Flex Builder 4. For more information, see and

Q: It says that API ___ no longer exists. Do you know what the replacement is?
A: Check out the list of Flex 4 SDK API renames for SDK builds after (Monday, June 15th week). The Flex SDK 4 beta 1 SDK was

10 thoughts on “Downloading and installing Flex 4 SDK builds from (Flash Builder 4 beta Edition)

  1. Thanks for the info Peter. To update the language reference, do we just overwrite the files in the

    \Flash Builder Beta\plugins\com.adobe.flexbuilder.help_4.0.0.235740\langref


    1. Greg,

      I’ve never tried swapping my language reference, but that may work. Not sure if it would impact the indexing or not though. I usually just use the online beta Language Reference docs, or else download a nightly build from the Flex 4 builds page and then unzip it locally to my desktop.


      1. I think I’ve asked somewhere and the answer was no, you can’t actually update your langref. Which is a bit of an issue anyway now that the FB can target two quite different versions of the SDK.

  2. Hello Peter,

    Is there a way to utilize the data visualization charts with the nightly builds? I understand why they are not included with these open source SDKs, but a number of projects we’re working on require data visualization. I’ve tried to simply copy over the datavisualization.swc, but I run into an error: Unable to resolve resource bundle “charts” for locale “en_US”. Any incite on this?

  3. NM, I seem to have figured it out. Copying over the datavisualization_rb.swc from “framework/lib/locale/en_US” fixes the issue.

  4. Thank you Peter for posting this clarification.
    There is another problem that was also reported on Adobe forum:

    The Component panel in the Design mode lists all the control components in the “Custom” folder and does NOT allow dragging any of the components to the stage. Although, you can place them in the source mode.
    I’m on MacBookPro OSX 10.5.7
    I have the screen shots.
    The Warning message is: Design View could not load spark.swc. It may be incompatible with this SDK, or invalid. (DesignSWFLoader.ERROR_LOAD_VERIFY)

  5. Hey,
    nice blog, really!
    Is there an option or a compiler setting to hide the embed file in the release build? In fact I would like have just one big file instead of having a couple of files and img-directories!


  6. I’ve tried to do with sdk 4 in flash builder 4.5, but it does not work. show me the error: “Directory does not contain a Flex SDK”. Why?

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