Update nightly Build Update or Full Package got after Login in Backend: Class 'JToolbarHelper' not found
Class 'JToolbarHelper' not found
4 (latest nightly build) macOS Sierra, 10.12.5 Firefox 53 (64-bit)
Same Error using joomla-cms-4.0-dev.zip
Fixed in 175e17a
Same error on joomla 3.4 Backend: Class 'JToolbarHelper' not found
Same Error using joomla-cms-4.0-dev.zip