Upgrade through webinterface doesn’t work well on those switches i think, so doing the upgrade through ios console is usually faster.
- Download the tar u want to upgrade to from cisco.com (login needed)
- Place the tar reachable for the tftp server (use jounin tftp server if u don’t have any other prefered one, http://tftpd32.jounin.net/tftpd32_download.html)
- Make sure firewall on your tftp machine/server is open for tftp or disabled
- Login to te switch ios console via serial/telnet/ssh
- IOS command: archive download-sw /overwrite /reload tftp://tftpserver_IP/c2960-lanbasek9-tar.150-2.SE4.tar
- Wait for the tftp download and the upgrade to finish, the switch will reboot