Unserialize error when viewing a contact
This would happen if you have an invalid value in your civicrm_setting table, if someone tried to manually edit one of the serialized values stored in there.

If you're not sure which value(s) might be problematic in that table, you can try editing the file at `Civi/Core/SettingsBag.php and insert this right after line 153 (note this is untested):



if ($dao-&gt;value !== NULL &amp;&amp; !unserialize($dao-&gt;value)) {
  CRM_Core_Error::debug('bad setting', $dao-&gt;name);
}


That should print the name of the bad setting on your screen.