apache/cassandra · error · RuntimeException

Exception occured while executing

Error message

Exception occured while executing %s

What it means

Variant of executeTask (without prePopulateSnapshots) that wraps any Throwable from task.call() into a RuntimeException 'Exception occured while executing <task>'. The real failure is always in the cause chain.

Solutions

  1. Read the 'Caused by' exception; fix the underlying issue it reports.
  2. Check disk space and permissions on data/snapshot directories for create failures.
  3. Re-run the specific snapshot command after remediation.
  4. For recurring scheduled failures, add cause-aware logging around executeTask callers.

Example fix

// before
String msg = ex.getMessage(); // "Exception occured while executing ..."
// after
Throwable root = ex; while (root.getCause() != null) root = root.getCause(); log.error(root.getMessage());
Defensive patterns

Strategy: try-catch

Try / catch

try { result = executeTask(task); } catch (RuntimeException e) { Throwable root = e; while (root.getCause() != null) root = root.getCause(); log.error("Root cause: {}", root.getMessage()); }

Prevention

When it happens

Trigger: Any AbstractSnapshotTask executed via this overload that throws — e.g. disk I/O failure while creating or clearing snapshots — is rethrown with this message.

Common situations: Snapshot creation/clearing invoked over JMX or scheduled (start, clearExpiredSnapshots) fails; the log shows this generic message instead of the root cause at top level.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/727d073970c2e3ad. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/service/snapshot/SnapshotManager.java:556

            prePopulateSnapshots(task);
            return task.call();
        }
        catch (Throwable t)
        {
            throw new RuntimeException(String.format("Exception occured while executing %s: %s", task.toString(), t.getMessage()), t);
        }
    }

    @VisibleForTesting
    <T> T executeTask(AbstractSnapshotTask<T> task)
    {
        try
        {
            return task.call();
        }
        catch (Throwable t)
        {
            throw new RuntimeException(String.format("Exception occured while executing %s", task.toString()), t);
        }
    }

    /**
     * Add table snapshots to snaphots cow list in advance in order to be sure that the snapshots to be created
     * are not existing already. "executeTask" method can be invoked by multiple threads, and they hit
     * this synchronized method which populates snapshots so next thread will fail to advance (exception is thrown)
     * if table snapshots of some other tasks are already present in snapshots cow list.
     *
     * Added snapshots to snapshot list are at this point "incomplete", they will not appear in listing output
     * until they are indeed taken and exist on disk, otherwise we would see "phantom" snapshots in listings,
     * they would be present but in fact they are just going through the process of being taken.
     *
     * @param task task to process
     */
    private synchronized void prePopulateSnapshots(TakeSnapshotTask task)
    {
        Map<ColumnFamilyStore, TableSnapshot> snapshotsToCreate = task.getSnapshotsToCreate();

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