Q: Netbeans compile error, why does it mean? I finished a Netbeans project a few months ago, it was successfully done, finished. But the strange thing is today I happen to look into it and recompiled it, haven't changed anything, but got the following error, I vaguely remember I encountered similar situations before, just recompile and it will be fine, but not this time, I recompiled a few times, same error, restarted the PC, and recompiled again, same error :
build-impl.xml:501: copylibs doesn't support the "indexMetaInf" attribute

I never touched this file and have no idea why it worked fine, but failed this time, what's wrong and what's the fix ?

A: It seems that the problem is in version of Ant and new Ant attribute indexMetaInf.
I have the same problem and think it'll be worth to explain how I've got it.
How to obtain the problem:
I use NetBeans 6.8.
Recently I installed NetBeans 7.0. Just for acquaintance with new features. 
I accepted to use old NB6.8 configuration, when NB7.0 asked me on the first launch.
That was mistake!
So. I started NB7.0 and my good old NB6.8 projects were there, in the projects list.
The problem is that NB7.0 not only imported my old projects in its projects list; but also
changed build-impl.xml of those projects.
And when I opened my projects in NB6.8 and tryed to compile them, there was that error with "indexMetaInf".
The essence of the problem:
In NB6.8 the Ant 1.7.1 is used, by default. And it seems that attribute "indexMetaInf" is only supported by 
latest versions of Ant (maybe starting with 1.8.x). That new version of Ant was installed with NB7.0 and is used by NB7.0 only.
NB6.8 doesn't see it.
How to fix the problem:
I updated build-impl.xml file from subversion and it fixed the problem.
In my previous version of build-impl.xml there was no indexMetaInf.

A: Had the same problem, fixed it by copying the file org-netbeans-modules-java-j2seproject-copylibstask.jar from [netbeans]\java\ant\extra into the directory myProject\lib\CopyLibs

A: Strange thing happened again, this time good. I had a backup DVD, from a few weeks ago, I copied the project back, now it's compiling fine again, seems to me the project somehow got corrupted, I did a C: drive defragmentation last week, could it somehow moved some files around and messed up a bit ? Anyhow, not a problem now.  

A: What platform are you using?  I've had some odd errors like that on Unix due to trying to compile the project from the command line and having a older version of ant in my path.
