Take a typical admin page like:

http://moodle.local/admin/settings.php?section=messageinbound_mailsettings

If you mess up the url you correctly get a section error exception:

http://moodle.local/admin/settings.php?section=notarealsection

Section error!

More information about this error

Debug info: 

Error code: sectionerror

Stack trace:

line 495 of /lib/setuplib.php: moodle_exception thrown

line 23 of /admin/settings.php: call to print_error()

However if you also a bump version file, or have installed a new version of a plugin, and try to load the real proper page you erroneously get the same code exception, when you should instead get a useful message saying an upgrade is needed (like you do in other places). This is particularly a pain in dev when plugin versions get bumped and you mistakenly think you've got a coding error when you don't.