Various little things broke: - tenantId is required as first parameter on most function calls (should be "public" instead if only single tenant is used, I believe). This is the most common issue. - getUserByEmail is gone - sendEmail has different types now - recipeUserId is required vs userId for some calls I don't think it would take more than a couple of hours work to update exactly what you have to be current with v16 All of the updates are explained in detail in the changelog, as well how to migrate the code: https://github.com/supertokens/supertokens-node/blob/master/CHANGELOG.md