Why can't I delete an invoice

Summary:

My question is the same as the one given into the user guide :

But even if my invoice

• is not validated.
• It's not matched to a purchase order or receipt.
• It's not updated with a tax calculation.
• It's has an approval status of Not required.

I cannot delete this invoice :

I get this error message :

I found some comments about this issue :

The gapless sequence is not a requirement at this level. Why am I not able to delete invoice even if the sequence is not defined as Gapless.

Is there any way to delete a such invoice ?

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