It sounds like you are trying this on a read-only filesystem. (mounted with option ro, or some other way) If that is the case, there is no way you can achieve what you are trying other than changing the read/write status of the filesystem in question.
With more details we can help you more:
at a minimum, look at the full path name and see how your filesystems are mounted
(output of mount). You can post both in your question by editing it and we might be able to help you more.
Edit: How to find that your mount options by using commandline mount:
DrSAR@localhost ~ mount
/dev/sdc2 on / type ext4 (rw,relatime,errors=remount-ro,data=ordered)
/var/lib/snapd/snaps/core_6673.snap on /snap/core/6673 type squashfs (ro,nodev,relatime,x-gdu.hide)
The details are not important except for the first option in brackets which states rw for read-write filesystems (like your main hard disk mounted at root /) or ro in the second case.
