These are the primary reasons for your HP Envy 6000 Printer Offline error.
It's possible that your HP Smart App isn't installed. Instead, your printer may not be properly linked to Wifi. Alternatively, this problem can be caused by a change in the printer's IP address or an out-of-date driver.
Another cause could be that the printer is not configured as the default or that the printer firmware needs to be updated. Lastly, this issue can happen if there are stuck tasks in the printing queue.