Looks like you upgraded from a version that wasn't in the archive, namely 5.6.25-3+deb.sury.org~trusty+1. Are you able to reproduce the issue in a clean install without that unofficial package?
Looks like you upgraded from a version that wasn't in the archive, namely 5.6.25- 3+deb.sury. org~trusty+ 1.
Are you able to reproduce the issue in a clean install without that unofficial package?