ramanathan1504 opened a new issue, #4243:
URL: https://github.com/apache/logging-log4j2/issues/4243
## Description
`CsvParameterLayout.toSerializable` passes `Message.getParameters()`
straight to
`CSVFormat.printRecord` without a null check. `getParameters()` returns
`null`
for any message type that has none — `SimpleMessage`, and therefore every
plain
`logger.info("some text")` call — so the layout throws a
`NullPointerException` for each such event.
`log4j-core/src/main/java/org/apache/logging/log4j/core/layout/CsvParameterLayout.java`,
lines 93–104:
```java
public String toSerializable(final LogEvent event) {
final Message message = event.getMessage();
final Object[] parameters = message.getParameters(); // null for
SimpleMessage
final StringBuilder buffer = getStringBuilder();
try {
getFormat().printRecord(buffer, parameters); // NPE here
return buffer.toString();
} catch (final IOException e) { // catches
IOException only
StatusLogger.getLogger().error(message, e);
return getFormat().getCommentMarker() + " " + e;
}
}
```
Only `IOException` is caught, so the NPE escapes into the appender. There it
is
reported through the `StatusLogger` and the application continues, which
means a
configuration using this layout produces one error per event and no output,
while
the JVM still exits 0.
A parameterised call such as `logger.info("order {}", id)` works, so the
failure
depends on which logging call is reached — a layout that appears to work in
testing can fail on the first plain-text message in production.
## Configuration
**Version:** reproduced on **2.26.1**. Present on both lines:
- 2.x `04c93c1d33` — `log4j-core/.../core/layout/CsvParameterLayout.java:98`
- 3.x `main` — `log4j-csv/.../csv/layout/CsvParameterLayout.java:104`
The 3.x copy moved into its own module and gained a recycler, but the null
check
is still absent and the `catch` still handles only `IOException`.
**Operating system:** macOS 15 (Darwin 25.5.0)
**JDK:** Temurin 21
## Logs
Captured against Log4j **2.26.1** on JDK 21, not reconstructed:
```
──── messages ── All Message types: Simple, Parameterized, Formatted,
MessageFormat, Object, Map, StructuredData, ThreadDump, Flow, Supplier
2026-08-05T18:07:16.257782Z main ERROR An exception occurred processing
Appender CsvParams
java.lang.NullPointerException: Cannot read the array length because
"values" is null
at org.apache.commons.csv.CSVFormat.printRecord(CSVFormat.java:2265)
at
org.apache.logging.log4j.core.layout.CsvParameterLayout.toSerializable(CsvParameterLayout.java:98)
at
org.apache.logging.log4j.core.layout.CsvParameterLayout.toSerializable(CsvParameterLayout.java:49)
at
org.apache.logging.log4j.core.layout.AbstractStringLayout.toByteArray(AbstractStringLayout.java:295)
at
org.apache.logging.log4j.core.layout.AbstractLayout.encode(AbstractLayout.java:207)
at
org.apache.logging.log4j.core.layout.AbstractLayout.encode(AbstractLayout.java:36)
at
org.apache.logging.log4j.core.appender.AbstractOutputStreamAppender.directEncodeEvent(AbstractOutputStreamAppender.java:227)
at
org.apache.logging.log4j.core.appender.AbstractOutputStreamAppender.tryAppend(AbstractOutputStreamAppender.java:220)
at
org.apache.logging.log4j.core.appender.AbstractOutputStreamAppender.append(AbstractOutputStreamAppender.java:211)
at
org.apache.logging.log4j.core.config.AppenderControl.tryCallAppender(AppenderControl.java:160)
at
org.apache.logging.log4j.core.config.AppenderControl.callAppender0(AppenderControl.java:133)
--
23:37:16.280 DEBUG o.a.l.b.s.MessageScenario - Supplier form — expensive
value: computed-lazily
23:37:16.281 INFO o.a.l.b.s.MessageScenario - Fluent API — LogBuilder with
location capture
```
## ## Reproduction
```xml
<Configuration status="warn">
<Appenders>
<File name="Csv" fileName="target/params.csv">
<CsvParameterLayout format="Default"/>
</File>
</Appenders>
<Loggers>
<Root level="info"><AppenderRef ref="Csv"/></Root>
</Loggers>
</Configuration>
```
```java
logger.info("order {} accepted", 4711); // fine: one parameter
logger.info("plain text"); // NPE, once, and the file gains
nothing
```
## Suggested fix
Treat a null parameter array as an empty record:
```java
final Object[] parameters = message.getParameters();
getFormat().printRecord(buffer, parameters == null ? EMPTY : parameters);
```
An empty CSV row is at least well-formed, and matches what the layout already
does for a message whose parameter array is present but zero-length.
Widening the
`catch` to `Exception` would stop the throw but leave the column count wrong,
which is worse for a format whose whole value is being machine-readable.
Whether a plain-text message should be silently dropped or rendered as an
empty
row is a design call, but the current behaviour — throwing per event — is
unlikely to be the intended one.
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