Disconnect the printer from the computer or network and turn it on and see if it comes to ready. If it does, then there is a print job trying to print that is confusing the printer. First you will want to delete all print jobs in the printq. Next you will want to upgrade the firmware. If none of this works see below:
49.4C02 or 49.4C06 error may be seen on the control panel when printing PDF files that contain malformed or incomplete fonts. This issue may also be seen when printing certain web pages that contain those fonts.
Potential workarounds are:
Print with PCL 5 driver
Print with a PCL6 or PS driver with the "Send TrueType as Bitmap" option enabled from the Advanced tab of the printer (driver) properties
When encountered while printing web pages, try a different web browser