Thanks Krileon - spot on as usual - so I did some phpmyadmin comprofiler investigation and discovered that for some reason a solid green canvas had become default with file name
canvas_735_5b1638a5e5878.jpg - which didnt exist on the server as you correctly pointed out
Used an update query to replace that particular canvas field entry to Null and then successfully upgraded the system to php 8.1.17 which is now delivering CB and CB Subs data accurately
swampy5