I attempted to update via the web UI to Unraid 6.9 RC1 from beta 29 and now I’m getting an error on boot up of:

 

SYSLINUX 6.03 EDD 2014-10-06 Copyright (C) 1994-2014 H. Peter Anvin et al

No DEFAULT or UI configuration directive found! 
boot: 

 

I searched the forum but there was nothing with this specific error. Am I hosed? Is my data safe on the drives? How do I get back to booting? 
 

I’m sorry for the tone of this as I’m kind of freaking out a little bit right now. :/ 

This is what the boot USB looks like as of right now: 

Backup the config folder, prepare flash as a new install, copy the config folder.

Okay, will attempt this now. Thank you! 

Looks like I cannot copy over much of the config folder: 

Do you have a recent backup of the flash drive?

Not at all sadly. I am running the usb through a data recovery now and hoping for the best. 

You must always have a current backup of flash. You can download a zipped copy of flash at any time from Main - Boot Device - Flash - Flash Backup. You can also schedule flash backups with the CA Backup plugin.

I'm having exactly the same issue. I have upgraded from 6.9.0-beta35 to 6.9.0-rc1 and now i am unable to boot.

 

I have made a backup of the flash drive recently, which i am restoring now.

Very possible these issues are the result of either flash device failure or corruption.  Try replacing the flash drive and see if these issues persist:

 

https://wiki.unraid.net/UnRAID_6/Changing_The_Flash_Device