Warning 5.6.0.3. In the statement of Theorem 5.6.0.2, the essential smallness assumption cannot be omitted: if the cocartesian fibration $U: \operatorname{\mathcal{E}}\rightarrow \operatorname{\mathcal{C}}$ is equivalent to $\int _{\operatorname{\mathcal{C}}} \mathscr {F}$ for some diagram $\mathscr {F}: \operatorname{\mathcal{C}}\rightarrow \operatorname{\mathcal{QC}}$, then each fiber $\operatorname{\mathcal{E}}_{C} = \{ C\} \times _{\operatorname{\mathcal{C}}} \operatorname{\mathcal{E}}$ is equivalent to the small $\infty $-category $\mathscr {F}(C)$ (see Example 5.6.2.18).
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