Boot failure after upgrading to Ubuntu 15.04

I have Sony Vaio Fit computer with a dual boot setup of Windows 8 and Ubuntu 14.10.

After upgrading to 15.04, booting into Linux fails with a number of 'builtin file not found' errors.

I tried toggling Secure Boot but that doesn't help.

The boot-repair info is at http://paste.ubuntu.com/12101145. If anybody has a suggestions, I would appreciate.

TIA