My webhost offers the ability to mirror a website, creating a subdomain. This means that the addresses in General Settings in WP are domainname.mirrorsvc.com Once the domain is purchased or transferred, one goes into the General Settings and changes it to domainname.com and then turns off the mirror. Voila, live site.
Most of the time this works flawlessly. Every once in a while it fails, apparently not right away, and maybe not even necessarily in the first couple of days. It may have to do with a WP upgrade.
Failure is characterized by most, sometimes all, of the images on the site not displaying. When you look at the img tag, the src references are still referencing domainname.mirrorsvc.com and once the mirror is turned off, that doesn't exist, therefore the image doesn't display. So in admin, you go to a page with an image, click the image, click the edit icon, click advanced settings and there's the problem. Under Advanced Image Settings, the source still refers to the domainname.mirrorsvc.com, instead of just the domain. Easy enough to change, but I want to know why sometimes that changes when you change the General Settings and sometimes it fails, and sometimes it fails for some images but not all.
I've occasionally seen something similar where after an upgrade, internal pages no longer display and they too show the subdomain in the address bar.
Anyone have any ideas why this happens sometimes?