Boot loop - Question on Big Sur beta 11.3

[ddublu]

I have a 2020 iMac with two TB 3 connections to two separate disk arrays (Thunderbay 4s) which also has two external monitors connected. After the most recent update to 11.3, my iMac boots to a login screen but as soon as I hit enter after my pword, it freezes briefly and then shuts down only to restart with a warning that it was shut down due to a problem. I can unplug the TB3 connections (but obviously lose all external data and both monitors).

I've pulled the power cable for 20 secs, restarted into safe mode, reset SMA and NVRAM with no luck. Any other suggestions?

 

[macsareveryinteresting]

Has there been any sort of damage to the monitors or the cables?

 

[ddublu]

Has there been any sort of damage to the monitors or the cables?

Nope. Was away on vacation last week and came back to the most recent update on startup. It's worked perfectly fine for the past few months on this iMac and equally as well on my prior iMac.

 

[macsareveryinteresting]

Nope. Was away on vacation last week and came back to the most recent update on startup. It's worked perfectly fine for the past few months on this iMac and equally as well on my prior iMac.

I know that unplugging the TB3 won’t be a good idea but it might work. It’s up to you. But it is also a risk. And and sure that the keyboard is functioning correctly.

 

[ddublu]

I know that unplugging the TB3 won’t be a good idea but it might work. It’s up to you. But it is also a risk. And and sure that the keyboard is functioning correctly.

I've unplugged both of them and it works fine but then I dont have my two external disk arrays with all of my data nor do I have my two external monitors.

 

[macsareveryinteresting]

I've unplugged both of them and it works fine but then I dont have my two external disk arrays with all of my data nor do I have my two external monitors.

Try restarting them.

 

[ddublu]

Try restarting them.

The monitors?

 

[ddublu]

Try restarting them.

I restarted the monitors. One thing I did notice. The TB3 connection between one monitor and my iMac works fine. It's the TB3 connected to the Thunderbay 4 disk array (which is connected to the second monitor) is what crashes and reboots back to login screen. Once I enter PW, it locks up and reboots.

 

[ddublu]

Looks like getting off of the beta is my only option. With all of my data on external drives, how far back in my TM backups do I need to go to get to a spot that is a normal Big Sur release?

 

[startergo]

try verbose mode with nvram boot-args="-v keepsyms=1 debug=0x144"