Invalid time zone 'UTC'

Listing the available timezones shows 'UTC'

$ timedatectl list-timezones
UTC

Setting it to UTC fails claiming UTC is "invalid".

$ timedatectl set-timezone UTC
Failed to set time zone: Invalid time zone 'UTC'

This is on Ubuntu 19.10 (Google Cloud)

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:  Ubuntu 19.10
Release:  19.10
Codename: eoan

Why is this failing?

Etc/UTC

You are missing Area code defined in the official tz database.

The time zone format is Area/Location. For most zones, the Area is a continent and the Location is a major city. For example, America/Montreal, Africa/Tunis, Asia/Tokyo, and Pacific/Auckland. Peruse this list.

Administrative zones have a special area: Etc. Therefore, the correct name for Coordinated Universal Time is Etc/UTC.

Appears to be a bug in your distro, they should package /usr/share/zoneinfo/UTC unconditionally, even if no other timezone data is installed. Please report this to your distribution.