For years I've felt confident that my system was idiot proof with only one button to click through the process.

Today a user proved me wrong.

Wow one button. What did they do?

Doubleclicked the button? 😀

right click print?

This proves the old adage: Make something idiot-proof and a better idiot will come along.

It's been 12h, can we please know what they did?

I can't wait for the OP to come up and tell us what happened.

I believe he has spent the last 16 hours debug what the user did wrong 😂😂😂😂

In short the user complained, but didn't answer questions as to what he did. Logs showed that he never pressed the final save button. So order was never completed and couldn't be printed or sent to processing.
User has been instructed to press the last save button. It's the only one there....