The checkalldomainsmxs fails if you add a domain without user and then run /scripts/updateuserdomains --force

Symptoms

The checkalldomainsmxs script fails with the following error if you have system domains (without user added via WHM) and run /scripts/updateuserdomains --force

Use of uninitialized value in string eq at /usr/local/cpanel/Cpanel/Proxy.pm line 207.

Description

The /etc/userdomains file is modified by /scripts/updateuserdomains --force which replaces the system user with nobody 

We've opened an internal case for our development team to investigate this further. For reference, the case number is CPANEL-46162. Follow this article to receive an email notification when a solution is published in the product. 

Workaround

Running the following oneliner will add the system domains back to the /etc/userdomainsand fix the system owner.

 /scripts/updateuserdomains --force; sed -i 's/nobody/system/g' /etc/userdomains