Debezium Could not Start Properly [DBZ-9391]

Migrated from [DBZ-9391](https://issues.redhat.com/browse/DBZ-9391)

In order to make your issue reports as actionable as possible, please provide the following information, depending on the issue type.
h1. Bug report

For bug reports, provide this information, please:
h2. What Debezium connector do you use and what version?

postgres connector & debezium v3.1.2.Final
h2. What is the connector configuration?

h2. What is the captured database version and mode of deployment?

debezium server on vm.
postgresql v15.13
h2. What behavior do you expect?

debezium started properly
h2. What behavior do you see?

Aug 26 02:49:39 db-ex bash[1927843]: 2025-08-26 02:49:39,633 WARN  [io.deb.con.pos.con.PostgresReplicationConnection] (debezium-postgresconnector-db-ex-change-event-source-coordinator) Failed to start replication stream at LSN\{332/E207D790}, waiting for PT10S ms and retrying, attempt number 1 over 6: org.postgresql.util.PSQLException: ERROR: replication slot "jb_slot" is active for PID 1929342
Aug 26 02:49:39 db-ex bash[1927843]:         at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2713)
Aug 26 02:49:39 db-ex bash[1927843]:         at org.postgresql.core.v3.QueryExecutorImpl.processCopyResults(QueryExecutorImpl.java:1299)
Aug 26 02:49:39 db-ex bash[1927843]:         at org.postgresql.core.v3.QueryExecutorImpl.startCopy(QueryExecutorImpl.java:968)
Aug 26 02:49:39 db-ex bash[1927843]:         at org.postgresql.core.v3.replication.V3ReplicationProtocol.initializeReplication(V3ReplicationProtocol.java:60)
Aug 26 02:49:39 db-ex bash[1927843]:         at org.postgresql.core.v3.replication.V3ReplicationProtocol.startLogical(V3ReplicationProtocol.java:44)
Aug 26 02:49:39 db-ex bash[1927843]:         at org.postgresql.replication.fluent.ReplicationStreamBuilder$1.start(ReplicationStreamBuilder.java:38)
Aug 26 02:49:39 db-ex bash[1927843]:         at org.postgresql.replication.fluent.logical.LogicalStreamBuilder.start(LogicalStreamBuilder.java:41)
Aug 26 02:49:39 db-ex bash[1927843]:         at io.debezium.connector.postgresql.connection.PostgresReplicationConnection.startPgReplicationStream(PostgresReplicationConnection.java:815)
Aug 26 02:49:39 db-ex bash[1927843]:         at io.debezium.connector.postgresql.connection.PostgresReplicationConnection.createReplicationStream(PostgresReplicationConnection.java:661)
Aug 26 02:49:39 db-ex bash[1927843]:         at io.debezium.connector.postgresql.connection.PostgresReplicationConnection.startStreaming(PostgresReplicationConnection.java:447)
Aug 26 02:49:39 db-ex bash[1927843]:         at io.debezium.connector.postgresql.PostgresStreamingChangeEventSource.execute(PostgresStreamingChangeEventSource.java:183)
Aug 26 02:49:39 db-ex bash[1927843]:         at io.debezium.connector.postgresql.PostgresStreamingChangeEventSource.execute(PostgresStreamingChangeEventSource.java:42)
Aug 26 02:49:39 db-ex bash[1927843]:         at io.debezium.pipeline.ChangeEventSourceCoordinator.streamEvents(ChangeEventSourceCoordinator.java:322)
Aug 26 02:49:39 db-ex bash[1927843]:         at io.debezium.pipeline.ChangeEventSourceCoordinator.executeChangeEventSources(ChangeEventSourceCoordinator.java:203)
Aug 26 02:49:39 db-ex bash[1927843]:         at io.debezium.pipeline.ChangeEventSourceCoordinator.lambda$start$0(ChangeEventSourceCoordinator.java:143)
Aug 26 02:49:39 db-ex bash[1927843]:         at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:572)
Aug 26 02:49:39 db-ex bash[1927843]:         at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317)
Aug 26 02:49:39 db-ex bash[1927843]:         at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
Aug 26 02:49:39 db-ex bash[1927843]:         at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)
Aug 26 02:49:39 db-ex bash[1927843]:         at java.base/java.lang.Thread.run(Thread.java:1583)
h2. Do you see the same behaviour using the latest released Debezium version?

(Ideally, also verify with latest Alpha/Beta/CR version)

h2. Do you have the connector logs, ideally from start till finish?

(You might be asked later to provide [DEBUG/TRACE|https://debezium.io/documentation/reference/stable/operations/logging.html] level log)

h2. How to reproduce the issue using our [tutorial|https://github.com/debezium/debezium-examples/tree/main/tutorial] deployment?

h1. Feature request or enhancement

For feature requests or enhancements, provide this information, please:
h2. Which use case/requirement will be addressed by the proposed feature?

h2. Implementation ideas (optional)

Start with the reported PostgreSQL replication-slot error and the PostgresReplicationConnection.startPgReplicationStream entry point named in the stack trace. First obtain the missing connector configuration, complete startup logs, version comparison, and tutorial reproduction requested by the report. Done requires a reproducible diagnosis and a confirmed resolution for the connector startup failure.

Written by the indexing model from the issue text.