We are missing form fields on the System Email Addresses dashboard page.
When debuggen i’m noticing and empty array in file:
public/concrete/single_pages/dashboard/system/mail/addresses.php
line 15 $senderConfiguration->getEntries()
Is it possible that you have an override of that file in your application/single_pages folder?
Or…
Have you setup the email addresses in the system & settings > email > system email addresses, if these are not setup that file will be unable to load completely.