Hello HONEYBUN8679,
Thanks for visiting Apple Support Communities.
It sounds like you see the error message "unsupported colorspace" when trying to print with your Epson Stylus DX8400. It can be hard to say why this error has occured, and there are some troubleshooting steps that can help resolve it.
First, make sure you've used Software Update to download the latest printer drivers, as mentioned here:
OS X: Printer and scanner software available for download - Apple Support
Use Software Update before connecting your printer or scanner. This updates the list of the latest supported printer and scanner models on your Mac. If you don't use Software Update before trying to connect a new printer, you might not see available software when you connect your device. If you're using a Wi-Fi printer, be sure to connect your printer to your Wi-Fi network before adding it to your Mac.
Next, remove the printer from the Printers & Scanners section of System Preferences, restart your Mac, and re-add the printer. See this troubleshooting guide for detailed help with this step:
Troubleshooting printer issues in OS X - Apple Support
Delete the affected printer, then add the printer again.
If you still see the error message, you may want to check with the manufacturer for additional printer software downloads and more help:
Contact the printer vendor or visit their website for further assistance.
EPSON
Company website
All the best,
Jeremy