JorgeB

Looks like this issue:
 
 

Looks like the Certificate provisioning server is down.

This

See this video:
https://forums.unraid.net/topic/129352-virtiofs-support-page/?do=findComment&comment=1178146
 

I didn't notice the errors on disk2 before, those are unrelated to the format problem, you should run an extended SMART test on that disk.

Run it again without -n or nothing will be done, if it asks for -L use it.

Controller problem:
 
Jan 2 09:06:02 Tower kernel: ata10.15: Port Multiplier detaching Jan 2 09:06:02 Tower kernel: ahci 0000:06:00.0: AHCI controller unavailable!  
Also avoid SATA port multipliers, see here for some recommendations.

The 500GB Samsung SSD was part of the pool in the past and is out of sync, disconnect that device and try again (or just wipe it).

Since there's nothing obvious in the log you can run another check to confirm all is well now, or just wait for the next scheduled one.

The problem was caused by the device dropping offline, and because of that likely the 2nd device never fully synced, so it's not able to repair, btrfs won't make devices drop offline, that's a hardware issue, with the device or board problem/compatibility issue.

No, it's XFS overheard.

That's a good idea, board next if it's not the PSU and you have another available.

Yep.
 
Unraid is not RAID, you can have one drive as parity and the remaining as data drives.

Btrfs is detecting data corruption on both devices:
 
Dec 29 21:24:42 cortex kernel: BTRFS info (device sdb1): bdev /dev/sdb1 errs: wr 0, rd 0, flush 0, corrupt 680, gen 0 Dec 29 21:24:42 cortex kernel: BTRFS info (device sdb1): bdev /dev/sdc1 errs: wr 0, rd 0, flush 0, corrupt 837, gen 0  
This suggests a RAM or other hardware problem, start by running memtest, once that's resolved you should run a scrub, any uncorrectable files should be deleted/restored from a backup, then reset the stats and keep monitoring.

One of your NVMe devices is slightly larger than the other, this can cause issues with a full filesystem since btrfs still sees free space on one of them, but because it's raid1 it cannot write to the other one, try disabling all services that use the pool, like VMs/dockers before array start and then start the array, without any new writes the fs might not go immediately read only.

Vdisks are thin provisioned, move to the array again then copy back with cp --sparse=always

You can do it manually, with for example Midnight Commander (mc on the console) or the Dynamix File Manager plugin, make sure you move the data form disk share to disk share, you can also use the Unbalance plugin.

Disk is not generating a complete SMART report, so it might be a disk issue, swap cables/slot with a different disk just to rule that out.

If you a re using FIrefox reboot first then try a different browser.

You could add them as a pool, they would need to be reformatted.

There's something writing to disk6, stop all other array i/o and it should improve.

For single device use xfs, for multi device use byrfs.

If parity is not 100% in sync only the bad part on the rebuilt disk would also be bad.
 
Yes, it might be better to re-enable only parity2, since if both are re-enabled only parity1 will be used to emulated the missing disk, assuming no read errors on a different disk.
 
The procedure would be the following (you need a new disk to replace disk23):
 
-Tools -> New Config -> Retain current configuration: All -> Apply
-Unassign parity1 and then check all assignments, parity2 must remain assigned as parity2, they are not interchangeable, assign any missing disk(s) if needed, including the new disk23, replacement disk should be same size or larger than the old one
-IMPORTANT - Check both "parity is already valid" and "maintenance mode" and start the array (note that the GUI will still show that data on parity disk(s) will be overwritten, this is normal as it doesn't account for the checkbox, but it won't be as long as it's checked)
-Stop array
-Unassign disk23
-Start array (in normal mode now), ideally the emulated disk will now mount and contents look correct, if it doesn't post new diags

 
 
 

Disk looks OK, since you've already done a new config check/replace cables and try again the parity sync.

You can also just backup current flash drive, recreate manually or by using the USB tool then restore only the /config folder from the backup.