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HP LaserJet Printers - Error "421 Print service not available"


the error 421 Print service not available error may be displayed when a file is pushed via FTP Prompt session.


  1. Check whether firewall is disable and not blocking the port.
  2. Enable FTP Printing in Embedded Web Server page (EWS) of printer.
Information about FTP Connections:
It is similar to standard FTP file transfer. FTP printing uses two TCP connections:
  1. Control connection
  2. Data connection
Once an FTP session is opened, it remains active until the client terminates the connection or the data and control connections are idle for 900 seconds (15 minutes). (This setting cannot be configured).
This is applicable for the printers which support FTP printing.