This happen when you have a name which is a reserved name or already exists by a table for example.
Lets say your are trying to add a new table and the error was:
org.postgresql.util.PSQLException: ERROR: syntax error at or near "User"
You got this error since the postgresql in the current schema has already a User table and this name is reserved.
Change your table (if in your case like this example, it's a table issue) name to a different.
Hoped it helps.