The most common mistake people make when using the word bienvenue is choosing the masculine ending when the feminine ending is needed.
When there is no verb in the sentence, you must choose the feminine form. This mistake happens frequently on signs welcoming people in various languages; many people just open a dictionary and choose a form. On a sign, since there is usually no verb preceding the welcome message, one would choose the feminine form.
- Masculine form: bienvenu
- Feminine form: bienvenue
- Bienvenue (Welcome)
- Bienvenue tout la monde (all are welcome)
- Soyez le bienvenu.
- Soyez la bienvenue.
- Soyez les bienvenus (or bienvenues if it's an all female group).