On Plesk for Linux server, scheduled task of type “Run a command” with curl or wget fails: SSL certificate problem: unable to get local issuer certificate

Symptoms

• On a Plesk for Linux server, a scheduled task of type Run a command with curl or wget (for example, curl https://example.com/some-url) fails:

  PLESK_INFO: SSL certificate problem: unable to get local issuer certificate

  PLESK_INFO: % Total % Received % Xferd Average Speed Time Time Time Current
  Dload Upload Total Spent Left Speed

  0 0 0 0 0 0 0 0 –:–:– –:–:– –:–:– 0
  0 0 0 0 0 0 0 0 –:–:– –:–:– –:–:– 0
  curl: (77) error setting certificate verify locations:
  CAfile: /etc/ssl/certs/ca-certificates.crt
  CApath: /etc/ssl/certs

  PLESK_INFO: ERROR: The certificate of ‘example.com’ is not trusted.
  ERROR: The certificate of ‘example.com’ hasn’t got a known issuer.

Cause

By default, scheduled tasks with the type Run a command are executed in the chrooted shell /bin/bash.
In this shell, there are no common CA certificates to verify SSL connections.

Resolution

Log in to Plesk and apply one of the solutions:

1. For server level tasks:

• Change the option Task type in the scheduled task to Fetch a URL.

• Change the default shell for scheduled tasks: go to Tools & Settings > Scheduled Tasks (Cron jobs) > Settings, select /bin/bash or /bin/sh in the option Crontab shell and click OK or Apply to save the changes.

2. For domain level tasks:

• Change the default shell for scheduled tasks: go to Domains > example.com > Web Hosting Access, select /bin/bash or /bin/sh in the option Access to the server over SSH and click OK or Apply to save the changes.