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Description

This error indicates that MongoDB encountered a command or operation that is not recognized, supported, or allowed in the current context. It often points to a malformed query, an unsupported feature usage, or an attempt to perform an action without proper authorization.

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Error Message

Illegal Operation

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Known Causes

4 known causes

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Using Unsupported Command or Feature

Attempting to execute a command or use a feature that is not available in your MongoDB version or is deprecated.

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Incorrect Command Syntax or Arguments

Providing malformed syntax or invalid parameters to a valid MongoDB command, leading to an unrecognizable instruction.

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Insufficient User Permissions

The authenticated user attempting the operation lacks the necessary roles or privileges to perform the requested action.

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Accessing Restricted Internal Resources

Attempting to directly modify or access internal MongoDB system collections or reserved databases not intended for user interaction.

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Solutions

4 solutions available

1. Review and Correct Malformed Queries easy

Identify and fix syntax errors or invalid operations within your MongoDB queries.

1

Examine the MongoDB logs for detailed information about the illegal operation. The error message might be accompanied by more specific details about the query or operation that failed.

2

Carefully review the query that triggered the error. Look for common mistakes such as:
- Incorrectly formatted operators (e.g., `$eq` instead of `$eq`)
- Missing or extra commas
- Unclosed braces or brackets
- Invalid field names or types
- Attempting to use operators in inappropriate contexts (e.g., using `$push` on a non-array field).

Example of a potentially problematic query (syntax check needed):
{
  "field": {
    "$gt": 10,
    "$lt": 5 // This condition is logically impossible and might trigger an error
  }
}

3

Test your queries in a MongoDB shell or a development environment to isolate the problematic part. Use `explain()` to understand the query execution plan if needed.

db.collection.find({ field: { $gt: 10, $lt: 5 } }).explain()

4

Correct any identified syntax or logical errors in the query and re-run the operation.

2. Validate Data Types and Schema medium

Ensure that the data you are querying or modifying conforms to expected types and schema constraints.

1

Inspect the documents involved in the operation that caused the error. Pay close attention to the data types of fields being queried or updated.

2

If you are using schema validation, review your validation rules. An illegal operation can occur if you attempt to insert or update data that violates these rules.

Example of a schema validation rule:
{
  "$jsonSchema": {
    "bsonType": "object",
    "properties": {
      "age": {
        "bsonType": "int",
        "minimum": 0
      }
    }
  }
}

3

Use MongoDB's `validate` command or tools like `mongosh` to check the integrity of your data and identify any inconsistencies.

db.collection.validate()

4

Correct any data type mismatches or schema violations. This might involve updating documents or adjusting your application's data handling logic.

3. Check for Invalid Index Operations medium

Ensure that index creation or modification operations are syntactically correct and adhere to MongoDB's index limitations.

1

If the error occurred during an index creation or modification operation, review the command used.

2

Verify that you are not attempting to create an invalid index, such as a multikey index on a field that is not an array, or an index with an unsupported type.

Example of an invalid index creation attempt:
// Assuming 'field' is not an array in your documents
db.collection.createIndex({ field: 1, 'nested.arrayField.$': 1 })
// Or an index on a geospatial field without the correct type

3

Consult the MongoDB documentation for the specific version you are using to understand valid index types and syntax.

4

Correct the index definition and re-run the index operation.

4. Investigate MongoDB Version Specific Issues advanced

Determine if the error is related to a known bug or limitation in your current MongoDB version.

1

Identify the exact MongoDB version you are running.

mongod --version

2

Search the official MongoDB Jira (bugs.mongodb.com) and release notes for known issues related to 'Illegal Operation Detected' or error code 20 for your specific version.

3

If a known bug is identified, check if there is a workaround provided or if upgrading to a newer patch or minor version resolves the issue.

4

Consider upgrading your MongoDB deployment to a more recent, stable version if you suspect a version-specific bug and no immediate workaround is available.

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Related Errors

5 related errors

MongoDB Error 20: Illegal Operation Detected