Can you enable debug = 2 in application/config/config.php and try again, please? Paste the complete error message here.

Sorry, I have no idea where application/config/config.php is. I have a community edition installed on my website. Would I have to ask the website administrator?
Currently, there is no error message.

No, it's OK, we can test it. Thank you for reporting the issue.

How you get to a survey with out a question?
Just create an empty survey and try to export?

That is how you could get there.
I wanted to report a bug in an existing survey. The bug was on the welcome page. So I copied it, deleted all questions for confidentiality and tried to export. Not possible, no error message, so I added a question, and the result is what i uploaded here.

I couldn't reproduce the issue. Can you please show a step by step explanation?

I couldn't reproduce the issue. Can you please show a step by step explanation?

Same,

1. Create survey with default question+group
2. delete question
3. delete group
4. export : you have an empty LSS survey.

Maybe you need to go to checkintegrity ?

Well trying. But now, I find no way to delete the only remaining question group. I cannot remember how I did it last time.

Check integrity? I find only "check data integrity" and "check question logic". That does not seem to apply, there are no data and questions.

Check integrity? I find only "check data integrity"

Yes : it's that, sometimes bug happen to base database …

I suggest you close this as unresolved, I will not pursue it further