I've been using an HP Officejet 6500 All-in-One for a few years now without any trouble. It is connected wirelessly to my network, for both printing & scanning. However, this week, scanning quit working, apparently as a result of some updates. After trying various things I found that it works fine connected using USB, but that's not a satisfactory fix.

I updated hplip to version 3.12.11 and tried reverting to the previous kernel version. Also, I've tried various scanner programs with varying failure messages such as the following hp-scan results:

3.5.0-20-generic x86-64 fails with:

Opening connection to device...

error: SANE: Invalid argument (code=4)

3.5.0-21-generic x86-64 fails with:

Expecting to read 10.9 MB from scanner.

Reading data: [|                                          ] 0%  0 B   

error: No data read.

Closing device.

Any suggestions are welcome.

Just realized that I should have made clear that printing still works well, via either wireless or USB.