Sudo askpass not working on macOS Sierra
Remove the line Defaults:ALL askpass=/Users/&lt;username&gt;/pass.txt from the file /etc/sudoers. I don't know the purpose of the line – at least it seems to be malformed compared to other Defaults entries and reading man sudoers.

A proper line may be: Path askpass = /Users/&lt;username&gt;/pass.txt. I can't test this though.