I was looking back through the mailing list archives and i found this email regarding failed inserts into the location table of a database due to duplicate entries and there is still a situation where this problem will occur. For the full original Thread, this is where is starts http://lists.iptel.org/pipermail/serusers/2004-April/007151.html http://lists.iptel.org/pipermail/serusers/2004-April/thread.html#7173 Basically the issue is that the database has an entry for a user that SER does not have in memory so when a registration comes in SER uses an INSERT statement instead of an UPDATE which fails because a key (username, contact, domain) already exists for the user in the database. The situation where it still occurs is when the database goes away and during the hiatus a registration expires, SER wipes the registration from memory and fails on the database delete. SER will recover from this situation only when it is stopped and started, this complicates load balanced situations where it is expected that SER can recover from certain failures (database failures in this case) without any administrive intervention