How I solved the Safari 13 and High Sierra problem with idmsa.apple.com unsecure connection (all Apple logins)
Like many other users since February I have encountered the "Safari 13.x - High Sierra" issue related to every Apple login service (iCloud, Apple store, developer.apple.com, Apple communities etc. ).
Here you can read some discussions concerning the issue:
https://discussions.apple.com/thread/251108056?answerId=252098530022&page=2
https://discussions.apple.com/thread/251210686
https://discussions.apple.com/thread/251196415
I tried everything, like them, without success. Then I found a solution that worked form me:
- Go on the Apple certificate page:
https://www.apple.com/certificateauthority/
Download the Apple Intermediate Certificates
- Double click the downloaded certificate to install it in Keychain Access.
- You should see it now, in login certificates.
Voilà, now Safari should be able to work like usual.
This is what worked for me and I hope for you too. 🙂