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Description

This error indicates that an `_id` field in a document or an ID used in a query does not adhere to MongoDB's expected data types or format. It typically occurs during database operations like inserts, updates, or lookups when the provided identifier is malformed or incompatible.

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Error Message

Invalid Id Field

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Known Causes

3 known causes

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Mismatched ID Data Type or Format

The ID provided for an operation does not match MongoDB's expected data type (e.g., `ObjectId`, string, number) or its specific format requirements.

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Invalid ObjectId String Format

A string intended to represent an `ObjectId` was malformed, typically by having an incorrect length (must be 24 hexadecimal characters) or containing non-hexadecimal characters.

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Querying with Malformed ID

An ID used within a query filter (e.g., `_id: 'invalid_id_value'`) does not conform to MongoDB's valid identifier formats, preventing the query from executing.

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Solutions

3 solutions available

1. Validate and Correct Document IDs medium

Inspect and fix malformed `_id` fields in your documents.

1

Identify the collection and documents that are causing the error. This often happens when trying to query or update a document with an invalid `_id`.

2

Connect to your MongoDB instance using the `mongo` shell or a GUI tool.

3

Use a query to find documents where the `_id` field might be malformed. MongoDB `_id` fields are typically `ObjectId` types. Look for non-string, non-ObjectId, or incorrectly formatted string `_id`s.

db.yourCollection.find({ _id: { $type: ['string', 'null', 'int', 'long', 'double', 'decimal', 'boolean', 'array', 'object', 'binData'] } })

4

For each identified malformed document, manually correct the `_id` field. If it's supposed to be an `ObjectId`, convert it. If it's a custom string ID, ensure it's a valid string.

db.yourCollection.updateOne({ _id: 'invalid_id_string' }, { $set: { _id: ObjectId('valid_object_id_string') } })

5

If you are inserting documents and receiving this error, ensure that the `_id` field, if provided, is either `null` (to let MongoDB generate an `ObjectId`) or a valid `ObjectId` string format before insertion.

db.yourCollection.insertOne({ _id: ObjectId('...') , field1: 'value1' });
// Or let MongoDB generate it
db.yourCollection.insertOne({ field1: 'value1' });

2. Check Application Code for ID Generation/Handling medium

Review your application's logic for how `_id`s are generated and used.

1

Examine the code responsible for inserting or updating documents in MongoDB. Pay close attention to how `_id` values are assigned.

2

Ensure that when you explicitly set an `_id`, you are using the correct MongoDB driver methods to generate or cast it to an `ObjectId` or a valid custom ID type.

const { ObjectId } = require('mongodb');
db.collection('yourCollection').insertOne({ _id: new ObjectId(), name: 'test' });
// Or for custom string IDs
db.collection('yourCollection').insertOne({ _id: 'my_custom_id_123', name: 'test' });

3

If your application is receiving `_id`s from an external source (e.g., user input, another API), validate and sanitize these IDs before using them in MongoDB operations. Ensure they conform to the expected `ObjectId` string format or your custom ID schema.

4

If you're using an ORM or ODM, consult its documentation for proper `_id` handling and ensure it's configured correctly.

3. Re-index Relevant Fields (If Custom IDs Are Used) easy

Ensure custom `_id` fields are properly indexed if they are not MongoDB's default `ObjectId`.

1

If you are using custom string or numerical values as your `_id` field, ensure it is properly indexed for efficient lookups.

2

Connect to your MongoDB instance.

3

Create an index on the `_id` field if it doesn't exist. This is usually done automatically by MongoDB, but it's good to verify, especially if you've changed ID types.

db.yourCollection.createIndex({ _id: 1 })

4

If you encounter issues with specific types of custom IDs (e.g., very long strings), consider if a different data type or a different approach to `_id` generation might be more suitable.

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Related Errors

5 related errors

MongoDB Error 53: Invalid Document ID Format