Unable to login after 8.4.2 upgrade

I don’t think there’s any way to revert the upgrade. The correct thing to do is revert to backups or snapshots.

The stack traces can be obtained from configuration settings, without any IDE set up.

I haven’t tried these myself in quite a while, I’ve made my own logging system, see this PR, but…

You can use a SuiteCRM config_override setting called $sugar_config[ā€˜stack_trace_errors’] = true;, see this for details.

And I think there is also a generic PHP setting, but I couldn’t find it just now. There are also option in Symfony, regarding ā€œdevā€ environment…