Xsession: warning: unable to write to /tmp

[mcc999]

Hello! I have the same problem, tried everything you've said bit still not working.

When checking my /tmp in terminal (running thought bootable USB) it shows its empty...

Filesystem      Size  Used Avail Use% Mounted on

udev            1.3G     0  1.3G   0% /dev
tmpfs           273M  1.4M  272M   1% /run
/dev/sdb        3.7G  1.8G  1.7G  52% /cdrom
/dev/loop0      1.6G  1.6G     0 100% /rofs
/cow            1.4G  114M  1.3G   9% /
tmpfs           1.4G   85M  1.3G   7% /dev/shm
tmpfs           5.0M  4.0K  5.0M   1% /run/lock
tmpfs           1.4G     0  1.4G   0% /sys/fs/cgroup
tmpfs           1.4G  532K  1.4G   1% /tmp
tmpfs           273M  8.0K  273M   1% /run/user/999

What else can I try?

I-m using lubuntu 20.04 LTS

Thanks in advance!