I have updated to 2.3.0 (MacOs / Intel) and imported a site from Live.
The new “port” settings are breaking site. I can not access subpages or wp-admin, as the “:{port}” part of the url gets lost and redirects to a url without the port number. It also looks like possibly the mysql replacement on the urls from live to local has broken.
I’m having the same issue with the URL replacement.
I can’t access anymore my dev site anymore, it redirects me to the live/staging site. I’ve checked my etc/hosts and even changed the address in MySQL, but it’s not working.
Welcome to DevKinsta @SBP ! I’m happy to help. Would you happen to have the URL entered into the wp-config.php file? If you have WP_HOME and WP_SITEURL entered into wp-config.php, try removing it and see if that helps.
For some reason, the response headers from the “site host” url incl. port number returns a redirect to the url without the port:
@SBP 
Hm. It states there in x-redirect-by: WordPress that the redirect is occurring from WordPress. Was there anything in the wp-config.php by chance?