Stretch upgrade causes camera problem

I am having trouble with the CSI camera on my DiddyBorg Mk1. The robot has 2 cameras, a Raspberry Pi CSI camera (mark 1 version) and an old USB web cam. I have had these working together for a couple of years without any problems, with Jessie and lately Stretch, until I did a recent Stretch update/upgrade. The CSI camera now reports the error "VIDIOC_QBUF: Invalid argument". (I get the same error trying 3 different cameras and different connector strips.)

The board in the robot is a Pi 3B (but I have the same problem with a couple of Pi 2Bs). I have also tried downloading a fresh Stretch image from the raspberry Pi web site and installing all my software on it (which took an age, especially the OpenCV) but still have the same problem.

Reverting back to my pre-upgrade backup Stretch installation and everything works as before.

for both cameras I am using the V4l2 driver initiated with "sudo modprobe bcm2835-v4l2". The web camera continues to work as before but not the CSI camera.

Taking a test frame using "raspistill -t 2000 -o test.jpg" works, proving that the camera is connected properly.

I realise that this is not strictly a PiBorg problem but I wondered if you had any ideas? To my simple mind the issue would seem to be with the V4l2 driver. I could continue without carrying out any further update/upgrades, sticking with the one that works, but that's not really in the spirit of things Raspberry Pi.