influxdata/influxdb · error · CatalogError

Field type mismatch on table

Error message

Field type mismatch on table {table_name} column {column_name}. Existing column is {existing} but attempted to add {attempted}

What it means

Thrown when a write or schema update tries to add a column (`column_name`) with a data type that differs from the type already stored for that column on the table. InfluxDB 3 columns have a fixed type once created; the error reports the existing type and the attempted type so the conflict is explicit.

Solutions

1. Cast the incoming value to the existing column type in the producer (e.g. write 72.0 for a float column)
2. Use a new column (or table) for the different type and migrate/backfill historical data
3. Normalize producer serialization so field types are stable (explicit schema/contract)
4. If the type genuinely must change, drop and recreate the table (data loss) or migrate to a new table

Example fix

// before: string where float exists
temp,room=1 value="72.5"
// after: match existing float column
temp,room=1 value=72.5

const col = schema.columns[columnName];
if (col && typeof value !== col.jsType) {
  value = coerce(value, col.type); // e.g. parseFloat(value) for float columns
}

function matchesColumnType(value: unknown, existing: ColumnType): boolean {
  switch (existing) {
    case 'float': return typeof value === 'number';
    case 'integer': return Number.isInteger(value);
    case 'string': return typeof value === 'string';
    case 'boolean': return typeof value === 'boolean';
  }
}

try {
  await write(points);
} catch (e) {
  if (/Field type mismatch/.test(String(e.message))) {
    // coerce types per the reported existing type and rewrite
  } throw e;
}

When it happens

Trigger: Writing a field whose value type differs from the column's established type — e.g. writing `temp="72"` (string) after the column was created as float; sending integer then float for the same field; producer code changes that alter serialization.

Common situations: Application upgrade changing a metric from integer to float (or vice versa); JSON payloads where values sometimes serialize as string; line protocol with a quoted number; multiple producers with inconsistent types for the same field name.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

• cannot add column because it already exists with type
• column id in series key should be valid
• column type mismatch for column
• Expected time column to have type Int64; instead found
• field does not exist

AI-assisted analysis of influxdata/influxdb@06200ef96b (2026-09-19). Data as JSON: /api/errors/2b057f7d2713a3e0. Report an issue: GitHub.

Appendix: source

Thrown at influxdb3_catalog/src/error.rs:183

    #[error(
        "table '{table_name}' in storage mode {storage_mode:?} cannot allocate more legacy column IDs"
    )]
    LegacyColumnIdsExhausted {
        table_name: Arc<str>,
        storage_mode: StorageMode,
    },

    #[error("Database not found {}", db_name)]
    DatabaseNotFound { db_name: Arc<str> },

    #[error("Table {} not in DB schema for {}", table_name, db_name)]
    TableNotFound {
        db_name: Arc<str>,
        table_name: Arc<str>,
    },

    #[error(
        "Field type mismatch on table {} column {}. Existing column is {} but attempted to add {}",
        table_name,
        column_name,
        existing,
        attempted
    )]
    FieldTypeMismatch {
        table_name: String,
        column_name: String,
        existing: InfluxColumnType,
        attempted: InfluxColumnType,
    },

    #[error(
        "Series key mismatch on table {}. Existing table has {}",
        table_name,
        existing
    )]

View on GitHub (pinned to 06200ef96b)