I met some issues with (at least) H2 and JdbcBinaryCacheStore that prevent to modify a value in the cache store which is quite annoying. After a deeper look, I realized that it was due to the method JdbcBinaryCacheStore.loadBucket(Integer keyHashCode) that uses setInt instead of setString like in updateBucket and insertBucket to set the id as parameter to the query. With HSQLDB and MySQL, it works normally but with H2, the result of the query is always empty so it always tries to add a new entry which of course fails because of the integrity constraint on the primary key (aka the id).