thanks!

just for clarification: i did't nothing at MXLinux that line was added in Devuan.

Good. Just so you know what that line does...

That says to mount sda3 (your MXLinux partition) at the root of the filesystem. Which means you would be running mx, not devuan.

Whereas, this line:

mounts the mx partition at /mnt, where it is available, but is not the system that's running at that time.

Changing '/dev/whatever' to 'UUID=' or 'LABEL=' is just a different way of identifying the partition. Sometimes it's necessary to do that. (e.g. multiple disks in the computer)

just for clarification: i did't nothing at MXLinux that line was added in Devuan.

Of course.  Sorry I didn't make that clearer.

Question:

and if from mxlinux i go to fstab and change what is over there:

# Pluggable devices are handled by uDev, they are not in fstab
/dev/sda3 / auto defaults,noatime 1 1

to this:

UUID=6e55911a-2620-4ab6-b2b5-1458602e6252       /       ext4    defaults,noatime        0       1
UUID=0b4a75ba-8b74-47b1-8aaa-2d971f92732f       swap    swap    defaults        0       0
LABEL=MXLinux    /mnt    auto defaults,noatime     0     0

Congratulations!!!!   Didn't I suggest exactly that here?

/dev/sda3 / auto defaults,noatime 1 1

for /dev/sda3: LABEL="MXLinux" UUID="66f3f330-78b2-4767-bc3e-8a9e7750e476" TYPE="ext4" PARTUUID="000f1103-03"

and this time it works!!

Thanks!!

Any way,

Thank you very much for your help!!

I'm back again, no it didn't blow up but nothing happened ...

Sad but it wasn't a big chance. Might try

yes

instead of auth_self if you aren't bored with it yet but i don't have all that much hope.

This is very likely unrelated. As shown by the blkid you posted on the last page your MXLinux partition uses ext4.

*About my previous commentary ... this time i got to read the whole line at the screen when restarted the system:

couldn't mount ext3 due to future incompatibilities

http://dev1galaxy.org/viewtopic.php?pid=9808#p9808

auth_self

(according to docs that should ask for authenticaten - root password?) or

yes

(which should just do it without further questions).

I am really stabbing in the dark here but i guess it's worth a try.

<message xml:lang="uk">Щоб змонтувати файлову систему, слід пройти розпізна$
    <message xml:lang="zh_CN">挂载文件系统需要身份验证</message>
    <message xml:lang="zh_TW">要掛載檔案系統需要先核對身分</message>
    <defaults>
      <allow_any>auth_admin</allow_any>
      <allow_inactive>auth_admin</allow_inactive>
      <allow_active>auth_admin_keep</allow_active>
    </defaults>
  </action>

Are you asking to change 'allow' for 'auth_self'?