EC
27
MongoDBERRORNotableQuery ErrorHIGH confidence

The specified index does not exist

What this means

This error occurs when an operation, most commonly `dropIndex`, refers to an index name or key pattern that does not exist on the specified collection. It can also happen if a query hint (`$hint`) specifies a non-existent index.

Why it happens
  1. 1Attempting to drop an index using a name or key pattern that does not match any existing index
  2. 2A typo in the index name provided to a `dropIndex` command or a query hint
  3. 3Trying to drop the default `_id` index, which is not allowed
  4. 4Race conditions where a concurrent process already dropped the index
How to reproduce

An attempt is made to drop an index using a name that does not exist.

trigger — this will error
trigger — this will error
db.products.createIndex({ category: 1 }, { name: "category_idx" });
// The following command fails because the name is wrong.
db.products.dropIndex("category_index"); // 'index' vs 'idx'

expected output

MongoServerError: IndexNotFound: index not found with name [category_index]

Fix 1

Verify the Index Name or Specification

WHEN Dropping an index or using a hint.

Verify the Index Name or Specification
// First, list the indexes to get the correct name.
db.products.getIndexes();

// Then, use the correct name to drop the index.
db.products.dropIndex("category_idx");

Why this works

Use the `getIndexes()` command to retrieve the exact names and key specifications for all indexes on the collection. Then use the correct identifier in your `dropIndex` or `$hint` command.

Fix 2

Use Key Pattern to Drop Index

WHEN You are unsure of the index's auto-generated name.

Use Key Pattern to Drop Index
// This drops the index based on its key structure, avoiding name issues.
db.products.dropIndex({ category: 1 });

Why this works

Instead of relying on the index name, you can provide the index key pattern document to `dropIndex`. This is often more reliable, especially for indexes without custom names.

What not to do

✕ Catch and ignore this error in a script that is supposed to clean up indexes

Ignoring the error can hide a typo or logical mistake in your deployment script. It is better to fail explicitly so you can be sure the intended index was actually dropped.

Sources
Official documentation ↗

mongodb/mongo src/mongo/base/error_codes.yml

Manage Indexes ↗

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