Civicrm - Expense extension [unable to edit expenses]
This sounds like it might be a bug in the expenses extension. It's hitting line 121 in CRM/Expenses/Form/Expense.php but $this-&gt;_expense is a string instead of an array at that point.
It's not clear why it's a string - it gets set at line 46 - if you add something like CRM_Core_Error::debug_log_message(var_export($this-&gt;_expense, true)); either at line 48 or at line 120 and then check in the ConfigAndLog file it will tell you what it looks like.