influxdata/influxdb · error · Error::MultipartFile

error decoding multipart file upload

Error message

error decoding multipart file upload: {0}

What it means

`Error::MultipartFile(String)` reports a failure while decoding a multipart file upload in the v1 API. When a request submits line-protocol or other data as a multipart form part, any parse/decode failure of that part is wrapped in this error with the underlying detail.

Solutions

1. Check the multipart field name matches what the API expects.
2. Validate the uploaded file is well-formed line protocol and correctly encoded (UTF-8).
3. Fall back to a non-multipart raw body upload if multipart is not required.

Example fix

// before
-F 'data=@points.txt'   // wrong field name
// after
-F 'file=@points.txt'   // expected part name

fn multipart_upload_ok(file: &[u8]) -> Result<(), String> {
    if file.is_empty() { return Err("empty file part".into()); }
    std::str::from_utf8(file).map_err(|e| e.to_string())?;
    Ok(())
}

fn is_multipart_error(e: &iox_v1_query_api::Error) -> Option<&str> {
    match e { iox_v1_query_api::Error::MultipartFile(m) => Some(m), _ => None }
}

multipart_upload_ok(&file_bytes)?;
let form = reqwest::multipart::Form::new().part("file", reqwest::multipart::Part::bytes(file_bytes));
let resp = client.post("/write").multipart(form).send().await?;

When it happens

Trigger: POSTing data via multipart/form-data where a part cannot be decoded — wrong field name, corrupt or non-UTF8 payload, or missing file part entirely.

Common situations: curl `-F` uploads with incorrect part names, CSV/line-protocol files with encoding problems, or clients that send multipart when the server expects a plain body.

Related errors

• authorization failure
• error decoding params from url
• error decoding query body
• invalid mime type ( )
• Invalid UTF8

AI-assisted analysis of influxdata/influxdb@06200ef96b (2026-09-19). Data as JSON: /api/errors/202c6c589807d51d. Report an issue: GitHub.

Appendix: source

Thrown at core/iox_v1_query_api/src/error.rs:32

pub struct QueryError(#[from] pub anyhow::Error);

#[derive(Debug, Error)]
pub enum Error {
    /// The requested path has no registered handler.
    #[error("not found: {0}")]
    NoHandler(String),

    #[error("authorization failure: {0}")]
    AuthorizationFailure(String),

    #[error("invalid mime type ({0})")]
    InvalidMimeType(String),

    /// Missing parameters for query
    #[error("missing query parameters 'db' and 'q'")]
    MissingQueryParams,

    #[error("error decoding multipart file upload: {0}")]
    MultipartFile(String),

    #[error("Invalid UTF8: {message} {error}")]
    Utf8 {
        message: &'static str,
        error: String,
    },

    /// Serde decode error
    #[error("error decoding params from url: {0}")]
    SerdeUrlDecoding(#[from] serde_urlencoded::de::Error),

    // SerdeJsonError
    #[error("error decoding query body: {0}")]
    SerdeJson(#[from] serde_json::Error),

    #[error("datafusion error: {0}")]
    Datafusion(#[from] DataFusionError),

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