The timezone could not be found in the database This one is new to me. I've got the timezone set in my admin panel to Denver but I get this this error when I try using a global in my template...

DateTime::__construct(): Failed to parse time string (End Date) at position 0 (E): The timezone could not be found in the database


Here is my code in the template

{{ endDate | date("U") }}


My global is called End Date (endDate) and is using a date field type
Is this a custom template global from a plugin or is it a field on a Craft global set, because those you usually access with {{ myGlobalSet.endDate }}.