Civicrm upgrade from 4.2.9 to 4.7.23
If you're getting an installation canary error, that means you tried upgrading once and it failed - and then when you upgraded a second time, you got the installation canary error.  The original error is the "true" error.  You can probably ffind it in your ConfigAndLog logs.  However, you should restore your pre-upgrade backup before attempting another upgrade.  Fixing a broken upgrade is a very advanced topic.