What do I need to do to upgrade unRAID from 6.0-beta12 to 6.0-beta14a?

 

Is this still valid:

5.0-rc9 through 5.0-rc16c

1. Prepare the flash: either shutdown your server and plug the flash into your PC or Stop the array and perform the following actions referencing the flash share on your network: Copy the files bzimage, bzroot, and syslinux.cfg from the zip file to the root of your flash device, overwriting the same-named files already there.

2. Reboot your server. Once boot-up has completed, you should see "Stopped. Configuration valid." array status with all disks assigned correctly. Some users have reported having to re-run 'make_bootable' script on the flash.

http://lime-technology.com/wiki/index.php/Upgrade_Instructions

Have you read the announcement thread for that release?

Now I did Thanks for the link.

I will probably stay on beta12 and wait little longer. But out of curiosity (and because I didn't do that yet), is mentioned upgrade process correct?

The upgrade process mentioned in that announcement thread is all you need to go from beta 12 to beta 14a

What do I need to do to upgrade unRAID from 6.0-beta12 to 6.0-beta14a?

 

Is this still valid:

5.0-rc9 through 5.0-rc16c

1. Prepare the flash: either shutdown your server and plug the flash into your PC or Stop the array and perform the following actions referencing the flash share on your network: Copy the files bzimage, bzroot, and syslinux.cfg from the zip file to the root of your flash device, overwriting the same-named files already there.

2. Reboot your server. Once boot-up has completed, you should see "Stopped. Configuration valid." array status with all disks assigned correctly. Some users have reported having to re-run 'make_bootable' script on the flash.

http://lime-technology.com/wiki/index.php/Upgrade_Instructions

This path is for 5.0-rc9 through 5.0-rc16c.  You are on 6.0beta12. So no, that method does not apply to you.