MFP 3301 Crashing After Automatic Firmware Update

[ER73]

On Friday (12/5/25), our MFP 3301cdw received an automatic firmware update to version 6.28.1.35-202511201716. This version does not exist on the official HP Support page. And, when I try to download what HP says is the current firmware (6.17.5.40-202503181735) it comes back with "file not found". 

With the update, we lost the ability to send documents via email. I had to unlink the printer from HP Cloud Connection (which had been disabled prior to the update) and re-added all of the email credentials. After that, we're also having intermittent issues with printing. There are "critical" errors showing in the log that are not documented, including codes: CD.2B.C9.06 and F0.31.08.09.

The printer had been working just fine until the firmware mysteriously updated. And, because we're out of warranty this is my only option for requesting support. Before we throw out the printer... any suggestions from the group or HP? Thank you!

[perf3ct]

Hey there, you're not crazy. I'm having the exact same issue, with the exact same symptoms. 

Updated on 12/5 -> 6.28.1.35-202511201716 (firmware completely bricks printer, just returns "Document format error")

I'm looking for firmware 6.17.5.34-202412122146, and even though it shows as an active download for "HP Color LaserJet Pro MFP 3301-3304 3388 Printer Series" printers, it just returns "Not Found". Thanks for wiping it off the face of the Earth HP. 

This printer is completely bricked and useless now, and can't even print a piece of paper. I've tried uninstalling and readding the device.

[Martin_FR54]

Same problem here on 2 MFP4302 !! Since auto update of the kernel to version 6.28.1.35-202511201716, When I print I got PCL XML ERROR Subsystem KERNEL