I am using Flex Builder 2.01.
I was attempting to follow the updated ModuleLoader documentation at Adobe blogs.
The directions included:To edit the list of runnable application files:
1. Right-click the project file and select properties.
2. Select the Flex Applications option.
The list of Flex applications appears in the dialog box. This list includes all MXML files
that were added as applications, regardless of their root tags.
You can add and remove modules from this dialog box by using the Add and Remove
buttons.
Well that dialog screen does not reflect your choices later, but also created in the problems tab the message
“An internal build error has occurred. Please check the Error Log.”
This is a catch all error when Flex Builder coughs up blood. Now I can see if you are messing with files outside of an integrated product you should be prepared to see the product cough. But I noticed in searching for this error message on the web, many folks have hit it in various ways while working inside of Flex Builder.
In my case I wanted to have a source folder called modules. The error was that I also needed to create manually a bin folder named modules. When you follow the directions above to set the modules as runnable, this does not occur automatically.
Well no matter what the reason for the error message you can find out more in a file in your workspace. This file is in the folder .metadata and is named .log. Once you open it you will see dumps of Flex corpuscles, a trace of its errors, and you can perhaps dig out the problem.
In my case it was simply
java.io.FileNotFoundException: C:\Documents and Settings\Lon\My Documents\Flex Builder 2\ModuleLoader\bin\modules\BarChartModule-debug.swf (The system cannot find the path specified)
Flex had been building these in the bin folder and only after I forced it to run them. Once I got the bin/modules folder created, it started doing this on its own.