Nono, I was a bit unclear. The point is that, if I understand the problem, GF always seems to think I've loaded JDBC 4 drivers, and tries to call JDBC 4 methods on my JDBC 3 drivers, and all exceptions are not equal.
PostgreSQLs JDBC 4 drivers throw a "org.postgresql.util.PSQLException, (...) xxxxxx() is not yet implemented" for all JDBC 4 methods, which GF catches, and continues processing normally. This gives me the page correctly anyhow, but a lot of gunk in server.log unless I up the loglevel. But with the JDBC 3 drivers there's no stub that throws an exception, and instead the JVM (IIUC) throws a java.lang.AbstractMethodError, which GF doesn't seem to catch, and the browser gets a HTTP 503 (I think) with the exception on.
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