UFL is a User Function Library. But more than likely your query re. what is UFL means you are not using one. Typically you'd know 
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Anyhow, I ran the report in a win app and it works fine. Now this is a saved data report. So the next question is; do you get the error running this same saved data report?
If it does, what happens when you refresh the report?
If a saved data report works, but refresh causes the issue, then I'd suspect that there is something that has changed in the database(?).
- Ludek