There are several reasons why HP ePrint Not Working. One common issue is that the printer and the device trying to connect to it are not on the same network. Another reason could be that the HP ePrint service is down or experiencing technical difficulties. It could also be that the printer software or firmware is outdated and needs to be updated. Additionally, the printer's email address or HP ePrint account may not be set up correctly. In some cases, the issue could be related to the device or app trying to access the printer. To troubleshoot, check your network connections, update software, check the status of the ePrint service, and double-check your account settings.