winston logger transport "write EPIPE" in CI

By Daniel Zoghalchali·Latchkey

EPIPE means a write went to a pipe whose reading end already closed. With winston, a Console or Stream transport keeps writing to stdout/stderr (or a custom stream) after the consumer, such as a piped tee or head, has exited, and Node raises "write EPIPE".

What this error means

A CI step logs "Error: write EPIPE" with a stack through @winstonjs/winston-transport and process.stdout.write, sometimes crashing the process after the test output was piped elsewhere.

Error: write EPIPE
    at afterWriteDispatched (node:internal/stream_base_commons:...)
    at writeGeneric (node:internal/stream_base_commons:...)
    emitted from winston Console transport

Common causes

The downstream reader of the log stream closed

Piping the job to head, tee, or a truncating consumer that exits early closes the pipe. Continued winston writes to that stream fail with EPIPE.

A custom stream transport whose target closed

A Stream transport pointed at a socket or file handle that was closed keeps receiving writes, producing EPIPE on the next log line.

How to fix it

Handle stream errors on the transport

1. Attach an error handler so an EPIPE on stdout does not crash the process.
2. Avoid piping CI output to a consumer that exits before the job.
3. Prefer file transports over fragile pipes for high-volume logs.

process.stdout.on('error', (err) => {
  if (err.code === 'EPIPE') return;   // downstream closed; ignore
  throw err;
});

Log to a file transport in CI

Write to a file instead of a pipe that a downstream tool may close early.

new winston.transports.File({ filename: 'ci.log' })

How to prevent it

• Attach an error handler to stdout / stream transports.
• Avoid piping job output to consumers that exit early.
• Use a file transport for heavy logging in CI.

Frequently asked questions

Related guides

References

• GitHub Actions documentation