databendlabs/databend · error · InvalidInput

failed to parse seq number

Error message

failed to parse seq number: {}

What it means

A validation guard in PermitKey::parse_key: the first segment of the key (the sequence number) must parse as a u64. This error fires when the leading segment before the last two slashes is not a valid unsigned integer, indicating the key was corrupted or written in a non-standard format rather than by format_key's {:020} formatting.

Solutions

1. Confirm the final path segment is a base-10 u64 sequence number with no whitespace, sign, or padding characters other than the expected zero-padding.
2. If the seq segment was truncated or corrupted in storage, re-encode the key with format_key.
3. Strip stray characters before parsing, or reject the key at a higher level if it fails u64::from_str semantics.

When it happens

Trigger: Thrown at src/meta/plugins/semaphore/src/storage/permit_key.rs:82 when the library encounters an invalid state.

Common situations: See trigger scenarios.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

AI-assisted analysis of databendlabs/databend@288d84d76e (2026-09-11). Data as JSON: /api/errors/70ab361e5bbcd046. Report an issue: GitHub.

Appendix: source

Thrown at src/meta/plugins/semaphore/src/storage/permit_key.rs:82

                format!(
                    "semaphore permit key should have at least 3 segments: {}",
                    key
                ),
            ));
        }

        if parts[1] != "queue" {
            return Err(io::Error::new(
                io::ErrorKind::InvalidInput,
                format!(
                    "semaphore permit key should have 'queue' as the second segment: {}",
                    key
                ),
            ));
        }

        let seq = parts[0].parse::<u64>().map_err(|e| {
            io::Error::new(
                io::ErrorKind::InvalidInput,
                format!("failed to parse seq number: {}", e),
            )
        })?;

        Ok(Self {
            prefix: parts[2].to_string(),
            seq,
        })
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_display() {

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