i am getting this error
Unexpected error encountered while preparing for the operation.
org.eclipse.core.runtime.AssertionFailException
and in the detail window
Unexpected error encountered while preparing for the operation.
null argument:
when i am try to update from this site http://mantis.faratasystems.com/downloads/update/site.xml
i am running eclipse 3.4.1 and flex builder as a plugin how can i correct this error and install this plugin (Fx2Ant)
For me, the new plugin installer "p2" gets often into an inconsistent state. My solution is to have three Eclipse installs: A work installation, a template and one "install". When I need to install some plugin, I delete the "install", copy it fresh from "template" and then do the install in there.
After the install, I copy the new files under "plugins" and "features" to my work installation into the directory eclipse/dropins/ + name of the plugin. See my blog for details.
Helpful as @Aaron's suggestion is, it is a bit tedious. I tried it out. In my case the copied plugins just wouldn't show up in the UI. Correcting the file permissions didn't help either and I gave up. Frustrated, I looked around for other resolutions to this bug and found one on the Eclipse wiki that can help you replace p2 with the original Update manager in Ganymede. I tried it out and it works. There is also an automated script available for download that does the same. I think this is a good solution till the issues with p2 get resolved.
You can read more about how to do this here.
Note: Works only for 3.4.x. It says that it will not work with 3.5 since p2 is tightly coupled with other components of 3.5.