XML : Getting errors with ant in netbeans, but no meaningful error message is produced

I am pretty new to Java EE and Netbeans in general. I am getting errors with my build-impl.xml file when I am trying to deploy a project to glassfish. The project consists of a client folder, an ejb folder and a common folder.

   <ant antfile="${project.202-slit-ejb}/build.xml" inheritall="false" target="dist-ear">          <property location="${build.dir}" name="dist.ear.dir"/>          <property name="deploy.on.save" value="${build.deploy.on.save}"/>      </ant>    <ant antfile="${project.202-slit-common}/build.xml" inheritall="false" target="jar">          <property name="deploy.on.save" value="false"/>      </ant>    <target depends="init" if="netbeans.automatic.build" name="-clean-after-automatic-build">      <antcall target="clean"/>  </target>    

These are code snippets from three errors I am getting. All of them followed by:

  The following error occurred while executing this line:    

Except for the last one, which is followed by:

   Unable to delete file C:\Users\User\Documents\NetbeansProjects\is202SLIT\Downloads\202-slit\202-slit-common\dist\202-slit-common.jar    

From netbeans output. I have no idea what to do with this information, and after an entire night of browsing I can't find any fixes to similar problems.

Is there any common error when trying to deploy project files? In addition, these files work fine on my friends computer, even though we have the same version of netbeans, and the same version of JDK. We can't get it to work on any computer other than his.

I have tried to clone the project numerous time, also tried to copy it without using git, nothing is working so far. Please tell me if you need more information.