Plugin is Defective or Outdated
When upgrading you might see an error like this:
Error code: detectedbrokenplugin * line 833 of /lib/upgradelib.php: plugin_defective_exception thrown * line 425 of /lib/upgradelib.php: call to upgrade_plugins_blocks() * line 1639 of /lib/upgradelib.php: call to upgrade_plugins() * line 465 of /admin/index.php: call to upgrade_noncore()
To see what self tests are occuring check the relevant class for the
_self_test() function for example in
blocks/moodleblock.class.php. The plugin needs to meet all the relevant criteria e.g. a title, appropriate content, applicable formats, preferred width etc.