@humet The error can only concatenate list (not "unicode") to list related to redirects made me think that perhaps you’ve formatted your site_hosts with a redirects value that is a string (unicode in Ansible) instead of as a list. I can reproduce the error above if I use the following format:
wordpress_sites:
example.com:
site_hosts:
- canonical: example.com
redirects: www.example.com
The error goes away if I format redirects as a list, like the default:
wordpress_sites:
example.com:
site_hosts:
- canonical: example.com
- redirects: www.example.com
+ redirects:
+ - www.example.com
+ - someotherdomain.com
The YAML for site_hosts can be a bit complex, if that kind of thing is unfamiliar. This final section of this attempted explanation of YAML for site_hosts may help.