dpkg sometimes says "subprocess post-installation script returned error
exit status 1". I had no situation where this error msg said me more
than "something went wrong during installation", yet a newbie will
suspect more information in the message (esp. the exit status), without
a clue how to interpret it or find out how to interpret it, and be
hopelessly lost.

I can see that the "post-installation" might be helpful in some
sitations. How about "Something went wrong during configuration.
Installation will be rolled back."? (Maybe find a better word for "roll
back".)