Fatal error: Uncaught exception 'Exception' with message 'DateTime::__construct(): Failed to parse time string (EST5EDT) at position 3 (5): Unexpected character' in
/myserver/mydirectory/nnnn/mysite/manager/controllers/default/dashboard/widget.grid-online.php:17 Stack trace: #0
/myserver/mydirectory/nnnn/mysite/manager/controllers/default/dashboard/widget.grid-online.php(17): DateTime->__construct('EST5EDT') #1
/myserver/mydirectory/nnnn/mysite/core/model/modx/moddashboardwidget.class.php(246): modDashboardWidgetWhoIsOnline->render() #2
/myserver/mydirectory/nnnn/mysite/core/model/modx/moddashboardwidget.class.php(118): modDashboardWidgetInterface->process() #3
/myserver/mydirectory/nnnn/mysite/core/model/modx/moddashboard.class.php(78): modDashboardWidget->getContent(Object(WelcomeManagerController)) #4
/myserver/mydirectory/nnnn/mysite/manager/controllers/default/welcome.class.php(64): modDashboard->render(Object(WelcomeManagerController)) #5
/myserver/mydirectory/nnnn/mysite/manager/controllers/default/dashboard/widget.grid-online.php on line 17
This question has been answered by BobRay. See the first response.
$datetime = new DateTime($timezone);
Are you seeing that in setup? If your core directory has been moved or renamed, setup is too dim to find it and you have to tell it where the core directory is. That will happen of you go to yoursite.com/setup.
If you're not seeing that while running Setup (in other words, you're just going to yoursite.com or yoursite.com/manager), it's possible that your site has been hacked (there's a lot of that going on lately). I would not respond to it in that case.
If it *is* Setup that's asking, in your MODX root directory (along with the setup, connectors, and manager directories), see if there's a core directory. If not, it's been moved and/or renamed.
There should be a config.core.php file in the MODX root. If you look in that file, you'll see the definition of MODX_CORE_PATH. You can paste that into the form in Setup.