OS X Capitan installation issues

My macbook is not successfully installing OS X Capitan. The update downloaded without a problem, but when my computer restarted the update will not install correctly and instead goes to a page of coding errors. I can't restore from a time machine back up, otherwise I'll lose a large quantity of my files. I have already run disk utility on all of my disks and it has made no changes to the restarting problem.

I was able to install OS X Yosemite without a problem when it came out, despite the age of my computer (2009 macbook).

Please help!