What causes "error while closing the snapshot file: %s" in hyperledger/fabric?

Only call Close() on the error/abandon path; rely on Done() to close on success

error while closing the snapshot file: %s

Error message

error while closing the snapshot file: %s

What it means

Close abandons the snapshot file (typically in a defer after an error) by closing the underlying file; the result of file.Close() is wrapped with this message. It can also wrap a double-close error if Done already closed the file — but note Close() returns nil when the receiver itself is nil. A non-nil return means the file descriptor could not be closed cleanly.

Source

Thrown at common/ledger/snapshot/file.go:119

	if err := c.bufWriter.Flush(); err != nil {
		return nil, errors.Wrapf(err, "error while flushing to the snapshot file: %s ", c.file.Name())
	}
	if err := c.file.Sync(); err != nil {
		return nil, err
	}
	if err := c.file.Close(); err != nil {
		return nil, errors.Wrapf(err, "error while closing the snapshot file: %s ", c.file.Name())
	}
	return c.hasher.Sum(nil), nil
}

// Close closes the underlying file, if not already done. A consumer can invoke this function if the consumer
// encountered some error and simply wants to abandon the snapshot file creation (typically, intended to be used in a defer statement)
func (c *FileWriter) Close() error {
	if c == nil {
		return nil
	}
	return errors.Wrapf(c.file.Close(), "error while closing the snapshot file: %s", c.file.Name())
}

// FileReader reads from a ledger snapshot file. This is expected to be used for loading the ledger snapshot data
// during bootstrapping a channel from snapshot. The data should be read, using the functions `DecodeXXX`,
// in the same sequence in which the data was written by the functions `EncodeXXX` in the `FileCreator`.
// Note that the FileReader does not verify the hash of stream and it is expected that the hash has been verified
// by the consumer. Later, if we decide to perform this, on-the-side, while loading the snapshot data, the FileRedear,
// like the FileCreator, would take a `hasher` as an input
type FileReader struct {
	file              *os.File
	bufReader         *bufio.Reader
	reusableByteSlice []byte
}

// OpenFile constructs a FileReader. This function returns an error if the format of the file, stored in the
// first byte, does not match with the expectedDataFormat
func OpenFile(filePath string, expectDataformat byte) (*FileReader, error) {
	file, err := os.Open(filePath)

View on GitHub (pinned to 2736b63f8f)

Solutions

Only call Close() on the error/abandon path; rely on Done() to close on success
Guard cleanup with a flag so Close isn't invoked after Done
Ignore or log the wrapped 'file already closed' error in deferred cleanup if Done succeeded

Example fix

// before
defer w.Close()
hash, err := w.Done()
// after
hash, err := w.Done()
if err != nil {
    defer w.Close() // close only on failure
}

Defensive patterns

Strategy: try-catch

Validate before calling

// guard: skip Close if Done already finalized
if done { return nil }

Try / catch

if cerr := w.Close(); cerr != nil && !strings.Contains(cerr.Error(), "already closed") {
    log.Warnf("snapshot cleanup: %v", cerr)
}

Prevention

Structure cleanup so Close runs only when Done failed or was not reached
Ignore benign 'file already closed' errors in deferred cleanup
Close is nil-receiver safe, but not double-call safe

When it happens

Trigger: Calling Close() after Done() already closed the file (yields 'file already closed' wrapped error), or Close() when the underlying close(2) syscall fails.

Common situations: defer w.Close() running after a successful Done(); duplicated cleanup in error paths; OS-level close errors on network mounts.

Related errors

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/71c7f3e9085fd343. Report an issue: GitHub.