Squid

You should contact support with the email address associated with your old forum account and they should be able to assist you.

Are you using any docker apps with dedicated IP addresses (or set to network type br0 with a dynamic address)
 
If so, you will attain higher stability by switching the network type from macvlan in Settings - Docker (with the service disabled) to be ipvlan.
 
Also (either caused by the crashes or bad memory) 
Feb 24 22:11:51 Helios kernel: BTRFS error (device nvme1n1p1): block=87024451584 write time tree block corruption detected Feb 24 22:11:51 Helios kernel: BTRFS: error (device nvme1n1p1) in btrfs_commit_transaction:2418: errno=-5 IO failure (Error while writing out transaction) Feb 24 22:11:51 Helios kernel: BTRFS info (device nvme1n1p1: state E): forced readonly I'll let @JorgeB advise on the btrfs recovery, but personally I'm not a fan of using BTRFS on single device pools.  You will always obtain better stability on the pools / filesystems by using XFS unless you require the features of btrfs (of which they are minimal on a single device)

You have what appears to be a docker container that is continually restarting.
 
The docker image is in the system share which is currently on the cache drive and disk 3.  Impossible to tell from diagnostics where the docker.img file is on which of those two drives, but if its on disk 3 then what you're seeing would be expected.
 
Go to Shares, next to system hit calculate.  If you see 100G (which may be overkill) on disk 3 then that's your issue.  Stop the entire docker service in settings - docker and run mover from the main tab

Check the connections to the cache drive.  It dropped completely offline

Enable Host Access To Docker Networks in Settings - Docker (Advanced View) with the service stopped

https://forums.unraid.net/topic/134016-fix-to-a-small-issue-with-updating-oci-docker-images/page/2/#comment-1220827
 

You really should post within the plugin's support thread

The penguin is for NFS shares.  SMB shares you want to click the windows icon.  Any problems with mounting though and you post in the UD support thread.

Start with running a memtest for at least a couple of complete passes

https://forums.unraid.net/topic/134016-fix-to-a-small-issue-with-updating-oci-docker-images/page/2/#comment-1220827
 

/boot/config/plugins/dockerMan/userprefs.cfg

Try using E1000 instead as the driver in the template.

Use this as a starting point
 
 
You'd of course have to modify the scripts with the appropriate commands to turn off the VM

Only the "root" user has access to the webUI to manage the server
 
All other users are used to access the files on the server via SMB, NFS etc

Mount the relevant shares from the other server via Unassigned Devices, and then pass those remote shares to your containers.  It's a very common setup / situation

Many containers (eg: 'arrs) also have additional options within their own settings to set the permissions on the particular files which they create.  Set the UMASK etc within their settings, or use permissions of 0777 in the settings.

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

Not an issue for you.  
 
This is what it's all about 
Dec 12 18:05:40 Tower mcelog: mcelog read: Function not implemented Googling that brings up only a single relevant reference, so not quite sure what to make of it, but I wouldn't worry

Did you also move the RAID card over or did the new server have a RAID onboard and you then created a new JBOD arrays with it.
 
RAID cards don't report the true serial numbers of the drives and basically append their own identifier to it. which is resulting in the system not identifying the drives as they were before.
 
You should do a Tools - New Config.  Then reassign all the drives into their appropriate places (make note of which is parity and which is data).  You can also check off parity is already valid, but you should run a parity check regardless.

Sans diagnostics, you're probably out of space in /tmp on the system.   A reboot is going to be necessary to recover.
 
Are you using Plex and transcoding to RAM (/tmp).  Plex (as per usual) is a PITA and has a nasty habit of never deleting it's temporary transcode files until playback is finished which means that /tmp can quite easily (and quite quickly) fill up

Because the folder /config/plugins/dockerMan/templates-user is corrupted and/or everything is deleted from it.  This is not anything (at all) related to the upgrade.
 
What is the contents of that folder?

Your flash.cfg file is trashed.  This is the contents
¹Él8û¶ÖÓ­[³Šx`Ũ»¦¢ÇAp øÂgÖïöÇ j\(ÝYá,™:Ô³¢¿,ãcÒ±¢/X$®‚e\‘ø÷2›…¶I,„^!ܑkdÊ°5pã(ÛåêÃ¥ ì†+M6O E7ÌËÿxjI\Yð‡L  
Delete /config/flash.cfg and then reboot
 
If problems continue, replace the flash drive

Gaps are fine and don't affect anything at all

Try changing the size of the image to 20G.  Possibly overhead etc involved in updating on the image