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Description

This error indicates that MongoDB received an unexpected or malformed value for an operation. It commonly occurs when data does not conform to the expected type, range, or structure required by the database or a specific field.

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Error Message

Bad Value

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Known Causes

4 known causes

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Mismatched Data Type

An attempt was made to store data of an incorrect type (e.g., string instead of number, object instead of array) into a field expecting a different BSON type.

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Out-of-Range or Invalid Value

A value provided for a field falls outside its permissible range or is not a recognized valid option (e.g., an invalid date, a non-existent enum value).

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Malformed BSON/JSON Input

The input data provided for an operation (e.g., an insert, update, or query parameter) is not valid BSON or JSON syntax.

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Schema Validation Failure

The data being inserted or updated violates defined schema validation rules for the collection, preventing the operation.

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Solutions

5 solutions available

1. Check Field Type easy

Ensure correct data type for field

1

Check expected types

// Common type mismatches:
// _id expects ObjectId, not string
// dates expect ISODate, not string
// numbers should not be strings

// Wrong:
db.users.find({ _id: "507f1f77bcf86cd799439011" })

// Right:
db.users.find({ _id: ObjectId("507f1f77bcf86cd799439011") })

2. Fix Query Syntax easy

Correct malformed query operators

1

Fix operator syntax

// Wrong:
db.users.find({ age: { gt: 18 } })  // Missing $

// Right:
db.users.find({ age: { $gt: 18 } })

2

Fix array operator syntax

// Wrong:
db.users.find({ $or: { status: "active", role: "admin" } })

// Right (array required):
db.users.find({ $or: [{ status: "active" }, { role: "admin" }] })

3. Fix Update Syntax easy

Use correct update operators

1

Use update operators

// Wrong (replaces entire document):
db.users.updateOne({ _id: id }, { name: "John" })

// Right (updates field):
db.users.updateOne({ _id: id }, { $set: { name: "John" } })

4. Fix Index Creation easy

Correct index specification format

1

Correct index syntax

// Wrong:
db.users.createIndex("email")

// Right:
db.users.createIndex({ email: 1 })  // 1 = ascending, -1 = descending

5. Fix Aggregation Pipeline medium

Correct pipeline stage syntax

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Fix pipeline structure

// Wrong:
db.users.aggregate({ $match: { status: "active" } })

// Right (array of stages):
db.users.aggregate([
  { $match: { status: "active" } },
  { $group: { _id: "$role", count: { $sum: 1 } } }
])

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Related Errors

5 related errors

MongoDB Error 2: Invalid Data Type or Format