There is a behaviour change in this version; previously a Throwable that occurred during a console command's run would be thrown upwards. It's now caught and turned into an Exception.

The change in question is here:
https://github.com/symfony/symfony/pull/22435/files#r115471431

For an example of how this causes an issue, in PhpSpec we maintain a 2.5 bugfix branch that does not know how to handle Throwables, instead relying on a mechanism that uses register_shutdown_function to format a nice error message when a fatal error occurs. As of Symfony 3.2.8 this message is no longer shown, because the shutdown function never executes.

This is something we could of course code around, but it's not a change I'd expect to be introduced in a patch.