pentaho/pentaho-kettle · error · KettleException

There was a problem retrieving a next sequence value from…

Error message

There was a problem retrieving a next sequence value from slave sequence '<slaveSequenceName>' on slave <slaveServer>

What it means

SlaveServer.getNextSlaveSequenceValue() wraps any failure while asking a slave server for the next value of a clustered ('slave') sequence into a KettleException. The HTTP call, the response parsing, or a non-numeric value returned by the slave all land here, chained as the cause. It means the master could not obtain a sequence value from the remote slave.

Solutions

Verify the slave server (Carte) is running and reachable from the master via its configured hostname/port.
Check the slave sequence exists on the slave (the transformation must create/register it before the master requests values).
Inspect the chained cause (KettleException.getCause()) for the root error (connect refused, 404, parse error).
Test the slave URL manually (e.g. GET http://slave:port/kettle/getSlaveSequence/) to see the raw response.
Retry the cluster run once the slave is healthy; sequence values are stateful so restart cleanly.
Validate the slave's hostname/port/username/password in the slave server definition (toString() in the message shows which slave).

Example fix

// before
long v = slaveServer.getNextSlaveSequenceValue("mySeq", 1); // throws on any slave hiccup
// after
try {
  long v = slaveServer.getNextSlaveSequenceValue("mySeq", 1);
} catch (KettleException e) {
  logError("Slave " + slaveServer.getName() + " failed to serve sequence: " + e.getCause(), e);
  throw e;
}

Defensive patterns

Strategy: try-catch

Validate before calling

// verify slave health before requesting sequence values
if (!slaveServer.getStatus().equals("OK")) {
  throw new IllegalStateException("Slave " + slaveServer.getName() + " is not reachable");
}

Try / catch

try { v = slaveServer.getNextSlaveSequenceValue(name, diff); } catch (KettleException e) { logError("slave sequence failed: " + e.getCause(), e); throw e; }

Prevention

Monitor Carte slave health before/during clustered runs
Pre-create the slave sequence on the slave before the master requests values
Log e.getCause() to capture the real network/HTTP error
Use consistent slave definitions (host/port/credentials) across the cluster

When it happens

Trigger: Calling getNextSlaveSequenceValue(slaveSequenceName, differential) on a SlaveServer whose /getSlaveSequence endpoint fails, returns an HTTP error, or returns a body that does not parse to a number (nextValueString non-numeric).

Common situations: Carte slave is down or unreachable mid-transformation; the slave sequence was not initialized on the slave; network/firewall drops the request; the slave returns an error page instead of the sequence value.

Understand the failure class

Background: 'Something went wrong' / 'Request failed (500)' / 'HTTP error! status: 404' — what failed HTTP requests actually mean and how to find the real cause — this error's family across 28 libraries.

Related errors

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/5c05fbe5fc3b4917. Report an issue: GitHub.

Appendix: source

Thrown at engine/src/main/java/org/pentaho/di/cluster/SlaveServer.java:1365

      String nextValueString = XMLHandler.getTagValue( seqNode, NextSequenceValueServlet.XML_TAG_VALUE );
      String errorString = XMLHandler.getTagValue( seqNode, NextSequenceValueServlet.XML_TAG_ERROR );

      if ( !Utils.isEmpty( errorString ) ) {
        throw new KettleException( errorString );
      }
      if ( Utils.isEmpty( nextValueString ) ) {
        throw new KettleException( "No value retrieved from slave sequence '" + slaveSequenceName + "' on slave "
          + toString() );
      }
      long nextValue = Const.toLong( nextValueString, Long.MIN_VALUE );
      if ( nextValue == Long.MIN_VALUE ) {
        throw new KettleException( "Incorrect value '" + nextValueString + "' retrieved from slave sequence '"
          + slaveSequenceName + "' on slave " + toString() );
      }

      return nextValue;
    } catch ( Exception e ) {
      throw new KettleException( "There was a problem retrieving a next sequence value from slave sequence '"
        + slaveSequenceName + "' on slave " + toString(), e );
    }
  }

  public SlaveServer getClient() {
    lock.readLock().lock();
    try {
      String pHostName = getHostname();
      String pPort = getPort();
      String name = MessageFormat.format( "Dynamic slave [{0}:{1}]", pHostName, pPort );
      SlaveServer client = new SlaveServer( name, pHostName, pPort, getUsername(), getPassword() );
      client.setSslMode( isSslMode() );
      return client;
    } finally {
      lock.readLock().unlock();
    }

  }

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