What did Napoleon Bonaparte temporarily permit around 1812 concerning older measurement units?

He allowed for the return of older, traditional units.

Despite the initial revolutionary mandate, the transition to the metric system was met with significant resistance domestically in France, especially among ordinary citizens and established businesses who were accustomed to the older, familiar units. Recognizing this difficulty and perhaps seeking broader societal compliance, Napoleon Bonaparte enacted a temporary measure around 1812. During this period, he allowed the coexistence or reintroduction of traditional units alongside the metric system. This acknowledgment of cultural inertia demonstrated that the theoretical superiority and clarity of the decimal system were not immediately sufficient to overcome deeply ingrained commercial habits and local practices.