Safari works everywhere by iCloud.com
Situation: friend has a Mac running High Sierra (currently) and the latest Safari, but there are two key websites that refuse to work — namely icloud.com and appleid.apple.com.— the spinner appears and never stops. Has been going on for "about a year" through two OS's and multiple Safari versions, and changing ISP's.
Have wiped cache files, removed all Extensions, done a "Shift launch", made sure Content Blockers/Popups, etc not being blocked, and moved the contents of ~/Library/Safari to the trash, but nothing changes the situation.
Applecare worked on the problem, couldn't solve it, and recommended wiping the hard drive and reinstalling the OS from Recovery mode.
These apple websites work fine in Chrome (which is the current workaround), but friend uses Safari for everything else. These websites come up on on the other family Mac.
I could try another user account, but the effort to move everything to a new user would not be worth the time, so that's not really an option.
Just wondering if anyone has run across the possibly simple answer to this one.
Please create a new user account and reproduce the steps that lead to the issue in the new user account. This will determine if the issue is system wide or user specific. Learning whether it is user specific or system wide will indeed tell us where to find search for the source of the issue, in the user's home folder or the system folder.
If testing in a new user account shows no issue then System files are ok which means that reinstalling the OS will not be a resolution step.
Your friend can search for and install EtreCheck and save the report, send it to you and attach it here in a reply. This will help find clues.
Hope this helps.
Do the pages load in an incognito window? https://support.apple.com/guide/safari/browse-in-private-ibrw1069/mac
If it works in a private window (incognito), try going into the Safari>Preferences and click on Manage Web Site Data, then search for Apple and remove any and all cookies belonging to Apple's domain. You can likely remove anything that comes up with the Apple name.
You can also try restarting the computer, the router and if still nothing try using a different DNS although the fact that Chrome is ok tells me these last steps are redundant.