Bonjour @MathildeDC,
It might be that the issue is the word "ensoleillé". That appears to be a registered trademark in the EU, USA, and other countries. Firefly excludes any registered trademarks to ensure it does not infringe on intellectual property rights.
However, when I translated the prompt to English, and tried that, it also failed. It appeared to be failing because of "sunny park". That also appears to be a registered trademark. I reworded it to "Two friends looking at camera smiling i
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