If you're trying to access your Templafy solution via a browser or the addins and are experiencing this error, you must activate TLS 1.0, 1.1 and 1.2 in Internet Options.
Microsoft removed the support for RC4 on all their Azure services and now only supports TLS.
See the below blog post for more info.
How to activate TLS in Internet Options
- Search for "Internet Options" in windows.
- Go to the "Advanced" tab
- Tick off "Use TLS 1.0", "Use TLS 1.1" and "Use TLS 1.2"
- Click "ok"
- Restart any application where you had the issue (Internet Explorer, Word, Outlook etc.)