O carregamento das configurações falhou ao iniciar o serviço prometheus no Ubuntu 18.04

Eu tenho um sistema operacional Ubuntu 18.04 e instalei prometheusnele seguindo as etapas aqui (apenas mudei links e versões).

Mas quando tentei iniciar o serviço com sudo systemctl start prometheus, recebi o seguinte erro em /var/log/syslog:

Jan 11 21:46:57 ZiZi prometheus[11585]: level=error ts=2020-01-11T18:16:57.051Z caller=main.go:727 err="error loading config from \"/etc/prometheus/prometheus.yml\": couldn't load configuration (--config.file=\"/etc/prometheus/prometheus.yml\"): parsing YAML file /etc/prometheus/prometheus.yml: yaml: unmarshal errors:\n  line 15: field static_configs not found in type config.plain"

Este é o conteúdo de /etc/prometheus/prometheus.yml(conforme descrito no tutorial mencionado acima):

global: 
 scrape_interval: 15s # Set the scrape interval to every 15 seconds.
 evaluation_interval: 15s # Evaluate rules every 15 seconds. 
 scrape_timeout: 15s # scrape_timeout is set to the global default (10s).

# A scrape configuration containing exactly one endpoint to scrape:# Here it's Prometheus itself.
scrape_configs:
 # The job name is added as a label `job=<job_name>` to any timeseries scraped from this config.
 - job_name: 'prometheus'

# metrics_path defaults to '/metrics'
 # scheme defaults to 'http'.

static_configs:
 - targets: ['localhost:9090']

Como posso corrigir o erro?