Retire essa linha.
"# Move /tmp to RAM
tmpfs /tmp tmpfs defaults,noexec,nosuid 0 0"
Deixe-o assim.
# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point> <type> <options> <dump> <pass>
proc /proc proc nodev,noexec,nosuid 0 0
# / was on /dev/sda6 during installation
UUID=4f0074cb-8288-4d7e-b120-99a31381ce07 / ext4 errors=remount-ro 0 1
# swap was on /dev/sda5 during installation
UUID=baf53c65-f10a-440b-b045-7791462ca7fc none swap sw 0 0
Agora, reinicie o computador e veja se resolve.
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