Hi, it seems that many people are having issues with the El Capitan kernel extensions.
Here is the list of the problematic kext files:
-bash-3.2# ls -1 Library/Extensions/ ; ls -1 Library/Application\ Support/VirtualBox ; find System/Library/Extensions/ -ctime +14w -depth 2
ACS6x.kext
ATTOCelerityFC8.kext
ATTOExpressSASHBA2.kext
ATTOExpressSASRAID2.kext
ArcMSR.kext
CalDigitHDProDrv.kext
HighPointIOP.kext
HighPointRR.kext
PromiseSTEX.kext
SoftRAID.kext
ls: Library/Application Support/VirtualBox: No such file or directory
-bash-3.2#
I booted into recovery mode and modified the ls commands to retrieve the appropriate values. I tried to remove as many problematic things as possible, but my MBP (early 2012 model) will still not boot.
Note: I had similar Mavericks upgrade problems as well, and had to do a time machine restore from a clean install. This is an upgrade from that.