influxdata/influxdb · critical · Error

error writing wal file

Error message

error writing wal file: {0}

What it means

Error::WriteError in influxdb3_wal wraps a failure to write to a WAL file. The underlying message is carried as a String. It indicates the durable append to the write-ahead log failed, which means writes could not be persisted.

Solutions

1. Check disk space and free capacity on the WAL volume (ENOSPC is the most common cause)
2. Verify filesystem permissions on the WAL directory
3. Inspect the inner message for the OS-level cause and remediate storage, then restart writes

// before writes: check writable & free space
let stat = fs2::free_space(&wal_dir)?;
if stat < min_free_bytes { return Err("WAL volume low on space".into()); }

match result {
    Ok(v) => v,
    Err(Error::WriteError(msg)) => { log::error!("WAL write failed: {}", msg); /* halt writes, alert operator */ },
    Err(e) => return Err(e),
}

When it happens

Trigger: The WAL writer's file append fails — disk I/O error, no space left on device, closed/rotated file handle — and the error is reported as a formatted string into Error::WriteError.

Common situations: Disk full (ENOSPC), permissions changed on the WAL directory, NFS/storage failures, container volume remounted read-only.

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

• IO error
• io error
• tempfile i/o
• another process has written to the WAL ahead of this one
• bitcode error

AI-assisted analysis of influxdata/influxdb@06200ef96b (2026-09-19). Data as JSON: /api/errors/56cf2d5d2b361cbb. Report an issue: GitHub.

Appendix: source

Thrown at influxdb3_wal/src/lib.rs:40

use rustc_hash::FxHasher;
use serde::{Deserialize, Serialize};
use serde_with::serde_as;
use std::cmp::Ordering;
use std::fmt::Debug;
use std::hash::BuildHasherDefault;
use std::str::FromStr;
use std::sync::Arc;
use std::time::Duration;
use std::{any::Any, num::ParseIntError};
use thiserror::Error;
use tokio::sync::{OwnedSemaphorePermit, oneshot};

#[derive(Debug, Error)]
pub enum Error {
    #[error("wal buffer full with {0} ops")]
    BufferFull(usize),

    #[error("error writing wal file: {0}")]
    WriteError(String),

    #[error("deserialize error: {0}")]
    Serialize(#[from] crate::serialize::Error),

    #[error("join error: {0}")]
    Join(#[from] tokio::task::JoinError),

    #[error("object store error: {0}")]
    ObjectStoreError(#[from] ::object_store::Error),

    #[error("wal is shutdown and not accepting writes")]
    Shutdown,

    #[error("invalid gen1 duration {0}. Must be one of 1m, 5m, 10m")]
    InvalidGen1Duration(String),

    #[error("invalid WAL file path")]

View on GitHub (pinned to 06200ef96b)