line 176: -4: substring expression < 0

[Dubzer]

Using: almost clear Ubuntu 18 on AWS
User: newbie in Linux =)

Here's a log what I do:

https://pastebin.com/rwiWquMU

[l-n-s]

OK, looks like your system already had wireguard cofiguration file before you ran the script. At least it had "/etc/wireguard/wg0.conf" installed. Try removing "/etc/wireguard/wg0.conf" file and start over.

[KoopaTroopas]

I am having the same issue as well. Ubuntu 18.04 droplet on Digital Ocean

[l-n-s]

It should not prompt for a client name on the first run of the script. If it does, then probably, your system already had previous wireguard installation.

[KoopaTroopas]

Yeah, I just saw your previous comment. Removing the wg-0.conf file did the trick

[ghost]

Delete the VM and create a new one.

[Dubzer]

Removing Wireguard config helped, thx