Magento 1 Dashboard chat is not working after upgraded to 1.9.4.1

I have upgraded Magento from version 1.9.3.7 to 1.9.4.1. After upgrading, the dashboard chart is not working.

Could see 503 Service Unavailable error when debugged:

a:5:{i:0;s:28:"Invalid header line detected";i:1;s:1304:"#0 /home/devabellioprojec/public_html/lib/Zend/Http/Response.php(696): Zend_Http_Response::extractHeaders('HTTP/2 200 \r\nda...')
#1 /home/devabellioprojec/public_html/lib/Zend/Http/Client.php(1110): Zend_Http_Response::fromString('HTTP/2 200 \r\nda...')
#2 /home/devabellioprojec/public_html/lib/Varien/Http/Client.php(61): Zend_Http_Client->request('GET')
#3 /home/devabellioprojec/public_html/app/code/core/Mage/Adminhtml/controllers/DashboardController.php(100): Varien_Http_Client->request('GET')
#4 /home/devabellioprojec/public_html/app/code/core/Mage/Core/Controller/Varien/Action.php(418): Mage_Adminhtml_DashboardController->tunnelAction()
#5 /home/devabellioprojec/public_html/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(254): Mage_Core_Controller_Varien_Action->dispatch('tunnel')
#6 /home/devabellioprojec/public_html/app/code/core/Mage/Core/Controller/Varien/Front.php(172): Mage_Core_Controller_Varien_Router_Standard->match(Object(Mage_Core_Controller_Request_Http))
#7 /home/devabellioprojec/public_html/app/code/core/Mage/Core/Model/App.php(365): Mage_Core_Controller_Varien_Front->dispatch()
#8 /home/devabellioprojec/public_html/app/Mage.php(686): Mage_Core_Model_App->run(Array)
#9 /home/devabellioprojec/public_html/index.php(91): Mage::run('', 'store')
#10 {main}";s:3:"url";s:642:"/index.php/admin_abl/dashboard/tunnel/key/704e7120617912e473bfcf2a829bb225/?ga=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&h=1596bf5a67149a9dbedc6b96f1f171d5";s:11:"script_name";s:10:"/index.php";s:4:"skin";s:5:"admin";}