JorgeB

It's not logged as disk problem , if possible try connecting that disk (and the other one from the same model) to the onboard SATA controller, this can also help:
 
 
 

You just need to backup the /config folder from the current flash drive, all you need is there.

That's correct, start the array to begin the parity sync.

https://wiki.unraid.net/Manual/Storage_Management#Rebuilding_a_drive_onto_itself

Feb 28 23:25:01 Truffle kernel: nvme nvme0: I/O 102 QID 3 timeout, aborting Feb 28 23:25:01 Truffle kernel: nvme nvme0: I/O 34 QID 4 timeout, aborting Feb 28 23:25:04 Truffle kernel: nvme nvme0: I/O 65 QID 2 timeout, aborting Feb 28 23:25:04 Truffle kernel: nvme nvme0: I/O 66 QID 2 timeout, aborting Feb 28 23:25:31 Truffle kernel: nvme nvme0: I/O 102 QID 3 timeout, reset controller Feb 28 23:25:34 Truffle kernel: nvme nvme0: I/O 8 QID 0 timeout, reset controller Feb 28 23:27:04 Truffle kernel: nvme nvme0: Device not ready; aborting reset, CSTS=0x1  
Device dropped offline, a power cycle should bring it back, not just a reboot, if it does this can sometimes help with these issues:
 
On the main GUI page click on the flash drive, scroll down to "Syslinux Configuration", make sure it's set to "menu view" (top right) and add this to your default boot option, after "append initrd=/bzroot"
nvme_core.default_ps_max_latency_us=0 pcie_aspm=off e.g.:
append initrd=/bzroot nvme_core.default_ps_max_latency_us=0 pcie_aspm=off
See if it helps.

File system has issues, suggest backing up anything important then try to repair, or possibly better just format the pool and restore the data.

Yep.
 
A backup, you can do it manually of for example with CA backup and restore.

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

It's using 62.6GiB
 
total used free shared buff/cache available Mem: 62Gi 1.8Gi 905Mi 1.1Gi 59Gi 59Gi  
You can ignore the 32

See here:
https://forums.unraid.net/topic/132930-drives-and-usb-devices-visible-in-bios-not-available-once-booted-asus-wrx80-sage-5965wx/?do=findComment&comment=1208035
 

Try using the disk path/share, user share always add some overhead.

Start here:
https://forums.unraid.net/topic/46802-faq-for-unraid-v6/?do=findComment&comment=819173
 

This should have been posted in the UD support thread, go to UD settings nad make sure the SMB settings are set to public, if that doesn't help post here:
 
 

Feb 24 13:22:14 unraid kernel: BTRFS info (device loop3): bdev /dev/loop3 errs: wr 0, rd 0, flush 0, corrupt 25, gen 0  
libvirt.img is also corrupt, but with that one if you re-create it you will need to reconfigure the VMs, do you have a backup?
 
Snapshots are supported, it's how I backup my VMs, there's just no GUI support, but you can take them manually (or with a script) or by using the Snapshot plugin.

https://wiki.unraid.net/Manual/Storage_Management#Rebuilding_a_drive_onto_itself

Check filesystem on disk4, run an extended SMART test on disk5.

If you are using Firefox reboot first the use a different browser.

Check filesystem on disks 1 and 12.

Check that the flash drive is being detected and set as the 1st boot option.

Make sure this is done and if yes enable the syslog server and post that after a crash.

Controllers with a SATA port multiplier are not recommended in general, but that by itself should not cause syn errors, unless it's a faulty controller, they are usually no good for performance and reliability issues.

One of you cache devices dropped offline in the past, run a correcting scrub and check that there are no uncorrectable errors, also see here for how to reset the errors and better pool monitoring.

Then looks like a compatibility issue between the NIC and that server, if it's not detected on a hardware level it will never work.

Stop array, click on that disk, change filesystem to xfs, start array, format.

Yes and yes.