Spring-data-jpa-duplicate-key-value-violates-unique-constraint May 2026

Use a repository method like existsByEmail(String email) before attempting a save. While this doesn't solve high-concurrency race conditions, it eliminates the majority of "honest" mistakes.

Passing a detached entity to the save() method can sometimes lead JPA to treat it as a new record (attempting an INSERT ) rather than an update, causing a primary key collision.

To handle these violations gracefully, developers typically employ one of three strategies: