So reviewing the screenshot attached I can comment on what I suspect is going on.
For firmware 2.0.8, folders are not supported from the SD card and therefore the UI-old.zip should be used. I’ll double check this and update the guide if that’s the case but based on your errors that’s what I am seeing.
For firmware 2.1.0, the issue might be an invalid line return character. This makes sense since its intermittent and most browsers and environments handle it fine. I will scan through my code and look if I can find the aberrant character, if I can.
In the meantime, could you try betaui.opensprinkler.com instead of ui.open….
If I find anything, I will push it to betaui and ask you to test again, if you don’t mind.
Thank you for the continued testing and feedback!