Dietpi-software Installation issues in V6.9

Hi,
I am using odroid xu4. I have installed dietpi 0s v6.9. I am not able to install softwares sucg as build-essentials and git from dietpi-software.
It displays error as follows:


After that I thought to install it using command line.Even at that point it is not yet installed as displayed error

So, I need to know whether v6.9 supports these installation.

Thanks

saiakash
Your APT repository looks a bid strange: cdstretch?

Could you try to reset it to default: /DietPi/dietpi/func/dietpi-set_softwarte apt-mirror default
and retry APT installations?