When you try to upload a large package to your instance, you get a message similar to the following error in the upload package dialog:
Testing package file.../day/cq-4.2/data/author/tmp/__uncgi45199.post Uploading package...day/cq-4.2/data/author/tmp/__uncgi45199.post error:java.io.EOFException: 448767 bytes expected, but read -1