1.2.18 add user error

[Luke <..hidden..>]

Hello

Received the following while trying to add a new user:

Error!

   UPDATE defaults
   SET value = ?
   WHERE setting_key = ?
   ERROR: current transaction is aborted, commands ignored until end of
   transaction block

That is while trying to add a user with the same name as an existing user, 
to implement the ..hidden.., ..hidden.. login process.

Any idea what is going on here?

Luke