Gaetan Collaud created KAFKA-20693:
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Summary: NPE in error handling in AbstractHerder
Key: KAFKA-20693
URL: https://issues.apache.org/jira/browse/KAFKA-20693
Project: Kafka
Issue Type: Bug
Components: connect
Affects Versions: 4.2.1
Reporter: Gaetan Collaud
When creating a connector using _PUT /connectors/abc/config_ and providing
wrong credentials for example for the Oracle database (when using
debezium-oracle) the REST endpoint returns something like this:
{code:java}
{
"error_code":500,
"message":"Cannot invoke
\"org.apache.kafka.connect.runtime.rest.entities.ConfigValueInfo.errors()\"
because the return value of
\"org.apache.kafka.connect.runtime.rest.entities.ConfigInfo.configValue()\" is
null"
} {code}
In the log, the full stack trace looks like this:
{code:java}
2026-06-15T16:05:28,860 ERROR || Uncaught exception in REST call to
/connectors/abc/config
[org.apache.kafka.connect.runtime.rest.errors.ConnectExceptionMapper]
java.lang.NullPointerException: Cannot invoke
"org.apache.kafka.connect.runtime.rest.entities.ConfigValueInfo.errors()"
because the return value of
"org.apache.kafka.connect.runtime.rest.entities.ConfigInfo.configValue()" is
null
at
org.apache.kafka.connect.runtime.AbstractHerder.maybeAddConfigErrors(AbstractHerder.java:1077)
at
org.apache.kafka.connect.runtime.distributed.DistributedHerder.lambda$doPutConnectorConfig$1(DistributedHerder.java:1144)
at
org.apache.kafka.connect.runtime.distributed.DistributedHerder.runRequest(DistributedHerder.java:2382)
at
org.apache.kafka.connect.runtime.distributed.DistributedHerder.tick(DistributedHerder.java:499)
at
org.apache.kafka.connect.runtime.distributed.DistributedHerder.run(DistributedHerder.java:384)
at
java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:572)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317)
at
java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
at
java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)
at java.base/java.lang.Thread.run(Thread.java:1583)
{code}
The actual error message (wrong credentials) can be found earlier in the log,
but the REST response is misleading and hides the root cause.
Source code causing issue:
[https://github.com/apache/kafka/blob/trunk/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/AbstractHerder.java#L1077]
Apparently the configValue can be null.
Looking at github, apparently some clean-up was done in this area, maybe it's
related, maybe not: [https://github.com/apache/kafka/pull/20393]
h2. How to reproduce:
Try to create an OracleConnector with an oracle that is not reachable or with
wrong credentials.
_config-connector.json_
{code:java}
{
"connector.class": "io.debezium.connector.oracle.OracleConnector",
"tasks.max": "1",
"database.hostname": "do.not.exists",
"database.port": "3333",
"database.user": "dbz",
"database.password": "secret3",
"database.dbname": "abc",
"schema.include.list": "a",
"table.include.list": "b.c"
} {code}
{code:java}
curl -X PUT -H "Content-type: application/json" -d @config-connector.json
localhost:8083/connectors/abc/config {code}
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