How I revived a dual boot Ubuntu/OSX system after upgrading to Mavericks

Preface: I had a healthy mid-2006 Mac Pro workstation with both Ubuntu 13.10 / Mac OSX Lion living happily alongside each other with the help of an old version of rEFIt (0.12). The system had survived many OS upgrades on both sides (From Ubuntu 11.10 upward and from OSX Leopard).

The Problem: When I upgraded the OSX from Lion to Mavericks (10.9), the system would not show any boot options and would directly boot into Mavericks. Holding “Option” key prior to boot would not show any other bootable partitions.

Things I tried:

#1 – Upgrade rEFIt to 0.14 (did not work): I knew rEFIt is no longer actively maintained, but I gave it a try. It did not change anything.

#2 – Install rEFInd (solved part of the problem): As you might already know, rEFInd is a successor to rEFIt. I downloaded the pre-built binary zip file for version (0.7.4), then installed it based on the this installation guide. After the reboot, the option to boot into Ubuntu partition showed up. However I was not able to boot into Ubuntu because I kept getting “No bootable device” error.

#3 – Made the partition bootable again using Ubuntu Live CD (solved the problem): If you search online for how to fix “no bootable device” error, you will find some frustrating guidelines. I had gone that way down before (on other systems) and I knew they might mess the whole partition table. Thanks to this great guide (step 10), the solution turned out to be quite simple: I booted the system using Ubuntu Live CD, fired up gparted, then [re]enabled the “boot flag” on Ubuntu’s root partition. One more reboot and the issue had been completely resolved.

I hope this post will help other people trying to resolve similar kind of issues.