apache/seatunnel · error · ConnectException

Invalid LSN returned from database

Error message

Invalid LSN returned from database

What it means

After successfully parsing the LSN in tryParseLsn, the code calls lsn.isValid(); if the parsed LSN is not valid it throws this ConnectException. This guards against LSN objects that parse syntactically but represent impossible positions (e.g. Lsn.INVALID), preventing the connector from starting from a bogus WAL offset.

Source

Thrown at seatunnel-connectors-v2/connector-cdc/connector-cdc-opengauss/src/main/java/io/debezium/connector/postgresql/connection/PostgresConnection.java:433

        if (lsnStr == null) {
            return null;
        }
        try {
            lsn = Lsn.valueOf(lsnStr);
        } catch (Exception e) {
            throw new ConnectException(
                    "Value "
                            + column
                            + " in the pg_replication_slots table for slot = '"
                            + slotName
                            + "', plugin = '"
                            + pluginName
                            + "', database = '"
                            + database
                            + "' is not valid. This is an abnormal situation and the database status should be checked.");
        }
        if (!lsn.isValid()) {
            throw new ConnectException("Invalid LSN returned from database");
        }
        return lsn;
    }

    /**
     * Drops a replication slot that was created on the DB
     *
     * @param slotName the name of the replication slot, may not be null
     * @return {@code true} if the slot was dropped, {@code false} otherwise
     */
    public boolean dropReplicationSlot(String slotName) {
        final int ATTEMPTS = 3;
        for (int i = 0; i < ATTEMPTS; i++) {
            try {
                execute("select pg_drop_replication_slot('" + slotName + "')");
                return true;
            } catch (SQLException e) {
                // slot is active

View on GitHub (pinned to cf67b549a7)

Solutions

1. Query the slot LSNs directly and compare against pg_current_wal_lsn() to see if the value is a plausible position.
2. Drop and recreate the replication slot so the server initializes confirmed_flush_lsn/restart_lsn to real WAL positions.
3. Let the server advance the slot: run a short transaction with the connector's plugin so WAL positions are established, then restart the connector.
4. Check database health/logs for corruption after unclean shutdowns and restart the instance if needed.

Example fix

-- before: slot reports an invalid sentinel LSN
SELECT pg_drop_replication_slot('seatunnel_slot');
-- after: recreate and prime the slot
SELECT pg_create_logical_replication_slot('seatunnel_slot', 'pgoutput');
BEGIN; INSERT INTO t VALUES (1); COMMIT; -- advance WAL, then start connector

SELECT restart_lsn, confirmed_flush_lsn, pg_current_wal_lsn() FROM pg_replication_slots WHERE slot_name = 'slot'; -- slot LSNs must be plausible relative to pg_current_wal_lsn()

try {
    connection.getReplicationSlotState(slotName, pluginName);
} catch (ConnectException e) {
    pgDropSlot(slotName); pgCreateSlot(slotName, pluginName);
}

When it happens

Trigger: The value in the given pg_replication_slots column parses via Lsn.valueOf but returns false from isValid() — typically the sentinel invalid LSN value or a numerically impossible position returned by the server.

Common situations: A freshly created slot whose LSN fields report an uninitialized/invalid sentinel on some server builds; a database fork (OpenGauss) returning non-standard sentinel values; catalog corruption after an unclean shutdown.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• Neither confirmed_flush_lsn nor restart_lsn could be found
• restart_lsn could be found
• Interrupted while waiting for valid replication slot info
• Unable to obtain valid replication slot. Make sure there are
• Value <column> in the pg_replication_slots table for slot =

AI-assisted analysis of apache/seatunnel@cf67b549a7 (2026-09-10). Data as JSON: /api/errors/c9df329810b3026a. Report an issue: GitHub.