Changes domain and now I get cookie error

Thanks, @otto42, I created a file with above at /home/malmesbury.xyz/public_html/wp-content/plugins/fix_cookies.php. Still same problem but guess I need to do something else to activate this?

wp-content/plugins/fix_cookies.php

I said “mu-plugins” for a reason.

/wp-content/mu-plugins/

@otto42, sorry misread that. Sorted it out and now it works, thanks a lot, you are a star.

Right! Glad to hear it.

For reference, that information can be found here:
https://danielbachhuber.com/2016/07/07/fixing-cookie_domain-for-mapped-domains-on-multisite/

The simple answer is that WordPress multisite does not fully handle multi-domain setups in this respect, and this quick fix will let you do that sort of thing. Domain mapping plugins do this, among other things, for you.