Steps to reproduce the issue

Install current staging with testing sample data
In article manager select multiple articles
Press batch on the toolbar
Select a tag eg red (same with all other batch options)
Click Process

Expected result

Batch action is performed

Actual result

Invalid controller: name='contact', format=''

If you have debug enabled then you will see further information

Call stack

Function Location

1 JApplicationCms->execute() /Applications/MAMP/htdocs/joomla-cms-staging/administrator/index.php:47
2 JApplicationAdministrator->doExecute() /Applications/MAMP/htdocs/joomla-cms-staging/libraries/cms/application/cms.php:252
3 JApplicationAdministrator->dispatch() /Applications/MAMP/htdocs/joomla-cms-staging/libraries/cms/application/administrator.php:152
4 JComponentHelper::renderComponent() /Applications/MAMP/htdocs/joomla-cms-staging/libraries/cms/application/administrator.php:98
5 JComponentHelper::executeComponent() /Applications/MAMP/htdocs/joomla-cms-staging/libraries/cms/component/helper.php:372
6 require_once() /Applications/MAMP/htdocs/joomla-cms-staging/libraries/cms/component/helper.php:392
7 JControllerLegacy::getInstance() /Applications/MAMP/htdocs/joomla-cms-staging/administrator/components/com_content/content.php:20
Return to Control Panel

System information (as much as possible)

This is with staging branch as at 09:00 GMT Tuesday 26 May

Additional comments