In confluence 2.7.3, the link "Download All " about the attachments of a page returns this error:

java.lang.NullPointerException at com.atlassian.confluence.servlet.download.ExportDownload.getStreamForDownload(ExportDownload.java:61) at com.atlassian.confluence.servlet.download.ServeAfterTransactionDownload$StreamResultCallback.doInTransaction(ServeAfterTransactionDownload.java:128) at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:127) at com.atlassian.confluence.servlet.download.ServeAfterTransactionDownload.getStreamInTransaction(ServeAfterTransactionDownload.java:40) at com.atlassian.confluence.servlet.download.ServeAfterTransactionDownload.serveFile(ServeAfterTransactionDownload.java:46) at com.atlassian.plugin.servlet.BaseFileServerServlet.doGet(BaseFileServerServlet.java:77) at javax.servlet.http.HttpServlet.service(HttpServlet.java:740) at javax.servlet.http.HttpServlet.service(HttpServlet.java:853) at weblogic.servlet.internal.ServletStubImpl$ServletInvocationAction.run(ServletStubImpl.java:1006) at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:419)

This was happening because the server context contained a capital letter, ie http://localhost:8080/confluenceWiki/

changing the context to all lowercase resolved the issue.