Could not close log file for

Error message

Could not close log file for %s. Creating new log file anyway.

What it means

FileRequestLogger rolls its request-log file each period. When closing the previous period's writer throws, CloseableUtils.closeAndSuppressExceptions logs this warning and the logger proceeds to open a new log file anyway. Data meant for the old writer may be lost, but request logging continues.

Solutions

Inspect the suppressed exception logged alongside this message for the root I/O cause.
Free disk space or fix permissions on the directory configured by druid.request.logging.dir.
Ensure the log directory is on a mounted, writable volume for the Druid process user.
If it recurs, restart the node to reopen a clean writer and confirm no other process owns the log file.

Example fix

// before: log dir on a full/rotated filesystem
druid.request.logging.dir=/var/log/druid (disk 100%)
// after: monitor/rotate externally and keep space available
druid.request.logging.dir=/var/log/druid  + logrotate with copytruncate and free-space alerts

Defensive patterns

Strategy: fallback

Try / catch

// FileRequestLogger already suppresses and continues; operators should alert on the log line:
// log.warn("Could not close log file for %s...") and its suppressed exception cause.

Prevention

Monitor free disk space on the request-log directory.
Do not rotate the file with external tools while Druid holds the writer.
Ensure the log directory is writable and mounted at all times.
Restart the node if roll failures recur to reopen a clean writer.

When it happens

Trigger: The scheduled roll task in FileRequestLogger.call() advances currentPeriodStart and calls CloseableUtils.closeAndSuppressExceptions(fileWriter, ...); the underlying writer's close() throws (disk full, filesystem error, stream already closed).

Common situations: Disk full or I/O errors on the log directory; log volume unmounted or read-only while rolling; concurrent external rotation of the same file.

Understand the failure class

Background: "failed to write file", "Could not save figure", "Error saving remote file" — file write failed: causes and fixes across languages and libraries — this error's family across 38 libraries.

Related errors

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/92997430ddbd86b5. Report an issue: GitHub.

Appendix: source

Thrown at server/src/main/java/org/apache/druid/server/log/FileRequestLogger.java:128

      long nextPeriodMillis = currentPeriodStart.plus(rollPeriod).getMillis();
      Duration initialDelay = new Duration(nextPeriodMillis - System.currentTimeMillis());

      ScheduledExecutors.scheduleWithFixedDelay(
          exec,
          initialDelay,
          rollPeriod,
          new Callable<>()
          {
            @Override
            public ScheduledExecutors.Signal call()
            {
              try {
                synchronized (lock) {
                  currentPeriodStart = currentPeriodStart.plus(rollPeriod);

                  CloseableUtils.closeAndSuppressExceptions(
                      fileWriter,
                      e -> log.warn("Could not close log file for %s. Creating new log file anyway.", currentPeriodStart)
                  );

                  fileWriter = getFileWriter();
                }
              }
              catch (Exception e) {
                throw new RuntimeException(e);
              }

              return ScheduledExecutors.Signal.REPEAT;
            }
          }
      );
      if (durationToRetain != null) {
        ScheduledExecutors.scheduleWithFixedDelay(
            exec,
            new Duration(0),
            Duration.standardDays(1),

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