I have upgraded both Prusa and Octoprint to 2.5 and 1.8 respectively. Upload to Octoprint now fails on a previously working setup. The "test connection" button works, and I have tried setting up both application and global APIs.
It is possible the raspberry pi is screwed up since it pushes voltage through the Ender3 units when they are powered off, and this problem emerged intermittently after startup of the ender3 units against a running raspberry pi unit with Octopi. But now it has settled in: prusa slicer now does not upload prints.
It is also possible I need to restart the household router after several reboots of the raspberry pi (my work VPN fequently screws up my local DNS when switching between ethernet and wifi on my work computer).
But what I need to do is rule out that there is some known issue with Prusa 2.5 and Octoprint 1.8. Is it possible that I need to do something special to restore upload-and-print capability between the Prusa and the Octoprint?