influxdata/influxdb · error · Error::InvalidContentType

unacceptable content-type, expected

Error message

unacceptable content-type, expected: {expected}

What it means

`Error::InvalidContentType` is returned when the request's `Content-Type` is not acceptable for the endpoint; the error message includes the `expected` MIME type parsed into `mime::Mime`. Handlers require a specific media type (e.g. text/plain for line protocol) to parse the body correctly.

Solutions

1. Set the Content-Type header to the expected value shown in the error message (e.g. text/plain for line protocol)
2. Match the endpoint to your payload format: JSON endpoints expect application/json, line protocol expects text/plain
3. Remove extra parameters from the Content-Type if they cause the mime parse/accept check to fail
4. Consult the endpoint docs in influxdb3_server for the accepted media types

Example fix

// before
curl -X POST http://localhost:8181/api/v3/write_lp?db=mydb -H 'Content-Type: application/json' --data-binary @metrics.lp
// after
curl -X POST http://localhost:8181/api/v3/write_lp?db=mydb -H 'Content-Type: text/plain' --data-binary @metrics.lp

function matchesExpected(ct, expectedPrefix) { return typeof ct === 'string' && ct.startsWith(expectedPrefix); }
// e.g. matchesExpected(headers['content-type'], 'text/plain') before calling write_lp

try { await writeLP(lines); } catch (e) { if (String(e).includes('unacceptable content-type')) { headers.set('Content-Type','text/plain'); retry(); } else throw e; }

When it happens

Trigger: POSTing line protocol without `Content-Type: text/plain` or application/xml variants the handler expects; sending JSON to a line-protocol endpoint or vice versa; missing Content-Type header entirely on strict handlers.

Common situations: Using the wrong endpoint for the payload format (v3 write_lp vs query JSON APIs), clients defaulting to application/x-www-form-urlencoded, or copying a curl example with an incorrect header.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• invalid mime type ( )
• invalid content-type header
• invalid mime type ( )
• invalid mime type ( )
• the mime type specified was not valid UTF8

AI-assisted analysis of influxdata/influxdb@06200ef96b (2026-09-19). Data as JSON: /api/errors/23397b59f8546d8e. Report an issue: GitHub.

Appendix: source

Thrown at influxdb3_server/src/http.rs:216

    /// The request body content is not valid utf8.
    #[error("body content is not valid utf8: {0}")]
    NonUtf8Body(Utf8Error),

    /// The `Content-Encoding` header is invalid and cannot be read.
    #[error("invalid content-encoding header: {0}")]
    NonUtf8ContentEncodingHeader(hyper::header::ToStrError),

    /// The `Content-Type` header is invalid and cannot be read.
    #[error("invalid content-type header: {0}")]
    NonUtf8ContentTypeHeader(hyper::header::ToStrError),

    /// The specified `Content-Encoding` is not acceptable.
    #[error("unacceptable content-encoding: {0}")]
    InvalidContentEncoding(String),

    /// The specified `Content-Type` is not acceptable.
    #[error("unacceptable content-type, expected: {expected}")]
    InvalidContentType { expected: mime::Mime },

    /// The client disconnected.
    #[error("client disconnected")]
    ClientHangup(Box<dyn std::error::Error + Send + Sync>),

    /// The client sent a request body that exceeds the configured maximum.
    #[error("max request size ({0} bytes) exceeded")]
    RequestSizeExceeded(usize),

    /// Decoding a gzip-compressed stream of data failed.
    #[error("error decoding gzip stream: {0}")]
    InvalidGzip(std::io::Error),

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

    /// DatabaseName validation error.

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