com.apple.xpc.launchd[1]: (com.apple.mrt[1153]) Service exited with abnormal code: 2

I do have the same on latest DP5

You need to temporarily disable SIP by booting into Recovery Mode (cmd+R):

Utilities > Security Configuration > uncheck "Enforce System Integrity Protection"

Then boot normally.

For now, if you want to prevent the conflict, you will have to keep SIP disabled.

SIP is a new security feature of El Capitan - something Yosemite and earlier didn't have - but while the kinks are still being worked out in beta it is causing some troubles.

If i do this:

(You need to temporarily disable SIP by booting into Recovery Mode (cmd+R):

Utilities > Security Configuration > uncheck "Enforce System Integrity Protection")

The messages arent ocurring any more.

But if i do the other ("Then boot normally. When you've confirmed that those console messages aren't occuring any more, boot back into Recovery Mode and re-enable SIP.")

The messages appears again

Okay, for now, if you want to prevent the conflict, you will have to keep SIP disabled (You will have to repeat the original step to disable it again).

SIP is a new security feature of El Capitan - something Yosemite and earlier didn't have - but while the kinks are still being worked out in beta it is causing some troubles. Sometimes the problem is sorted out by just turning it off for one boot, sometimes you have to keep it off. This is one of those "keep it off" times.

I will change my original reply to reflect this.

It would be good to report this bug here: https://bugreport.apple.com so that in a future beta this will be properly fixed and you can turn SIP back on again.

Thanks!!