Thank you for reaching out to us through the Community. I am sorry to hear that you are experiencing this issue. Does the "unexplained error" also occur after you have attempted to enter the contact into your database? Could you also provide us with a screenshot of the error message? Also, have you tried to add these contacts within another browser to see if it is potentially not a browser-related issue? Does the same error come up if you try to use the option of "Type or Paste In Multiple Contacts" or is it only happening when you type in one contact at a time?