| Formfehler | Nominativ, Singular | nominative case, singular | |
| Formfehler(e)s | Genitiv, Singular | genitive case, singular | |
| Formfehler(e) | Dativ, Singular | dative case, singular | |
| Formfehler | Akkusativ, Singular | accusative case, singular | |
| Formfehlere | Nominativ, Plural | nominative case, plural | |
| Formfehlere | Genitiv, Plural | genitive case, plural | |
| Formfehleren | Dativ, Plural | dative case, plural | |
| Formfehlere | Akkusativ, Plural | accusative case, plural |