Release Notes for MongoDB 8.3

Important

MongoDB 8.3 is the latest minor release. Starting with MongoDB 8.2, minor releases are available for on-premises deployments (Community and EA) for specific use cases. For more information, see MongoDB Versioning.

To install the latest MongoDB version supported for on-premises use, see the installation instructions.

Patch Releases

8.3.13 - Sept 24, 2026

Issues fixed:

SERVER-127294 Fix race in NetworkInterfaceTest.NumRequestsTimedOutBeforeSentToRemoteMetric

All JIRA issues closed in 8.3.13

8.3.13 Changelog

8.3.11 - Sept 11, 2026

This release contains important security and reliability improvements.

Important

MongoDB 8.3.11 contains a fix for:

CVE-2026-89099

For the latest information about MongoDB security updates, see MongoDB Security Bulletins.

Issues fixed:

SERVER-134063 Shred collection validator constants during parsing
All JIRA issues closed in 8.3.11

8.3.9 - Sept 8, 2026

This release contains important security and reliability improvements.

Important

MongoDB 8.3.9 contains fixes for:

For the latest information about MongoDB security updates, see MongoDB Security Bulletins.

Issues fixed:

SERVER-87919 Stop taking unstable checkpoints during recovery for restore
SERVER-96874 Replication recovery can crash due to concurrent shutdown
SERVER-125742 Remove the graceful exit for kernel version 7.0.14 and above
SERVER-132246 minWaitForStreamingHelloMillis default breaks spec-compliant drivers
SERVER-130571 Limit use of $_internalIndexKey to internal clients only
SERVER-130926 Usage of strtoll in generateJSONSchemaArraySingleSchemaError can throw std::exception
SERVER-130495 WiredTigerRecordStore configString allows overriding WiredTiger value_format
SERVER-130306 Fix heap-use-after-free in TextMatchExpression
SERVER-130202 Clean up stale state in GeometryContainer when GeoJSON parsing fails
SERVER-130901 Limit JSON Pointer path depth to 255 for $jsonSchema.encryptMetadata.keyId
SERVER-130785 Fix LDAP roles for pooled LDAP connections
SERVER-128253 Integer overflow in query planner explodeForSort() can trigger mongod denial of service
SERVER-132650 Make mongos use the configurable minimum timeout for pre-auth streamable hello
SERVER-132125 Ban $_isHybridSearch at top-level agg command requests
SERVER-131860 Improve wiredtiger config string handling
SERVER-131423 Apply consistent redaction in reportState()
SERVER-132835 Query shape for $search leaks raw query literals on mongos
SERVER-131326 Repeat stmtIds on writes crash the server
SERVER-131229 enforce case-sensitivity in options validation
SERVER-131562 Heap memory disclosure via mis-indexed tie-break vectors in the query multi-planner
SERVER-131420 Reject WiredTiger configString type overrides other than "type=file"
SERVER-130759 Adjust invariant condition to account for arbiter nodes
SERVER-131870 Fix heap use-after-free
SERVER-131138 Disallow user-initiated applyOps on containers
SERVER-130907 Use after free possible with memory tracking and two cursors
SERVER-131202 Fix aggregation pipeline updateLookup with dollar-prefixed fields
SERVER-127985 Reject regex matches that do not lay on UTF-8 character boundaries
All JIRA issues closed in 8.3.9
8.3.9 Changelog

8.3.8 - Aug 11, 2026

This release contains important security and reliability improvements.

Important

MongoDB 8.3.8 contains fixes for:

For the latest information about MongoDB security updates, see MongoDB Security Bulletins.

Issues fixed:

SERVER-123864 Improve $lookup local-read fallback in sharded_agg_helpers
SERVER-127863 Enforce authenticationMechanisms on the SASL MONGODB-X509 path
SERVER-128392 Duplicate insert into a clustered collection whose _id contains a Decimal128 throws a KeyString format error
SERVER-128482 Disallow $documents with $_resumeAfter or $_startAt
SERVER-128551 Fix initialization order of $unwind in $graphLookup
SERVER-129460 Ensure valid jsonSchema in time series updates
SERVER-129617 Better validation for NaN in $percentile and $median
SERVER-129618 Disallow user-provided $vectorSearch arguments from overriding internally generated options
SERVER-129887 Fix a collision in bucket OIDs during bucket allocation that leaves a dangling pointer to the bucket
SERVER-129936 Tighten validation of $idLookup internal fields
SERVER-129994 Fix a malformed FlatBSON store caused by inserting duplicate field names
SERVER-130110 Gate the internal-only _internalSetObjToThis field of $function behind an internal-client check
SERVER-130111 Prevent invalid type conversion during match expression serialization
SERVER-130117 Fix a heap use-after-free in collection validation for big polygons
SERVER-130139 Account for the o-versus-UUID consistency check
SERVER-130167 Stop the JavaScript scope from constructing delete requests by concatenating unsanitized _id fields
SERVER-130188 Exclude partial indexes from 2dsphere geometry skip-validation
SERVER-130198 Increase the authorization requirement for slowms and sampleRate in the profile command
SERVER-130247 Treat Decimal128 values as potentially invalid when preparing to yield or detach a cursor
SERVER-130264 Apply the intra-cluster SASL mechanism allowlist in egress connection setup
SERVER-130266 Prohibit $text and $near in $_internalSchemaCond
SERVER-130481 Allow the symbol type in CommandHelpers::parseNsFromCommand
SERVER-130544 Enforce the internal user for commitTransaction and abortTransaction on prepared transactions
SERVER-130628 Prevent excessive range padding insertions into the ESC during FLE2 compaction
SERVER-130633 Authorize compactStructuredEncryptionData and cleanupStructuredEncryptionData at database scope
All JIRA issues closed in 8.3.8
8.3.8 Changelog

8.3.7 - July 22, 2026

This release contains important security and reliability improvements.

Important

MongoDB 8.3.7 contains fixes for:

For the latest information about MongoDB security updates, see MongoDB Security Bulletins.

Issues fixed:

SERVER-123081 Handle compound wildcard index spec in $_internalIndexKey
SERVER-124355 Improve memory checks for array expressions to prevent huge in-memory arrays from $concatArrays combined with $range
SERVER-125872 Fix exponential hashing of query solutions for InternalSchema*MatchExpression nodes
SERVER-126247 Properly validate $search.mergingPipeline as an internal-only field
SERVER-127280 Reject expression-based sortBy in the $linearFill parser
SERVER-127357 Check for duplicate from fields in DocumentSourceGraphLookup::createFromBson()
SERVER-127566 Limit the contention factor that can be used for FLE2 fields
SERVER-127661 Require autocommit when startOrContinueTransaction is specified
SERVER-127689 Only allow internal clients to specify $_internalPredicate
SERVER-127694 Add type checking for DBPointer
SERVER-127737 Limit the number of metadata blocks allowed in a FLE2IndexedTextEncryptedValue
SERVER-127831 Forbid external users from running FLE2 commands with crudProcessed set to true
SERVER-128198 Fix mongos killCursors to check authorization against the cursor's namespace instead of the request namespace
SERVER-128316 Bound the maximum typo suggestion in hybrid search
SERVER-128341 Fix a server crash caused by sorting on a $meta expression
SERVER-129103 Restrict target BinData subtypes in $convert and $constant/$literal
SERVER-128362 Add a null check on the return value in ocspClientCallback
SERVER-128387 Remove auth role parsing from SSL TLVs in the proxy protocol parser
SERVER-128433 Prevent external clients from setting runtimeConstants.userRoles
SERVER-128473 Fix a use-after-free in $function caused by a missing advanceGeneration() call on retained BSON arguments
SERVER-128494 Validate external BSON in MultiBsonStreamCursor
SERVER-128517 Add a configurable minimum timeout for pre-auth streamable hello to prevent a hot loop from very small maxAwaitTimeMS values
SERVER-128584 Add memory checks for $convert from BinData to an array
SERVER-128832 Guard ImplScope ModuleLoader creation
SERVER-79980 Support TLS 1.3 for Windows
SERVER-83322 Compound Wildcard Index bounds reverts to [MinKey, MaxKey] when filter contains fields outside CWI
SERVER-108215 Impose limits on the number of active multi-document transactions
SERVER-127346 Make session refresh have kExempt admission priority
All JIRA issues closed in 8.3.7
8.3.7 Changelog

8.3.4 - June 11, 2026

Important

MongoDB 8.3.4 contains a fix for CVE-2026-11933

For the latest information about MongoDB security updates, see MongoDB Security Bulletins.

Issues fixed:

SERVER-128125 Align bsonObjToArray ownership semantics with bsonGetImmutable
All JIRA issues closed in 8.3.4
8.3.4 Changelog

8.3.3 - June 9, 2026

Important

MongoDB 8.3.3 contains a fix for:

For the latest information about MongoDB security updates, see MongoDB Security Bulletins.

Cost-Based Ranker:

Starting in MongoDB 8.3, multi-planning with a CBR backup is the default plan selection mechanism for eligible queries. For a short trial period, the multi-planner attempts to find a plan capable of returning a result set within this short timeframe. If the attempt is unsuccessful, MongoDB applies a set of rules to determine whether the multi-planner should continue or if CBR should evaluate each node in the plan to determine the optimal plan.

SERVER-118434 Makes the CBR eligible for use during query planning
SERVER-115402 Adds explain output to the CBR
SERVER-120369 Adds serverStatus metrics for the CBR
SERVER-117199 Adds $queryStats metrics for the CBR

For more information, see Query Plan Options.

Issues fixed:

SERVER-115250 Pause JWKSetRefreshJob during quiesce time
SERVER-121822 Clustered collections do not correctly filter out results with $lt on _id
SERVER-125887 Add support for encrypted PEM fules for gRPC egress
SERVER-126049 MozJS per-scope heap limit check uses process-global GC counter
WT-16780 Insufficient error context in WT_PANIC checkpoint failures in __wt_block_checkpoint_resolve
SERVER-126506 Remove SASL params from egress logging
SERVER-125063 Prohibit nesting of BSONColumn inside BSONColumn
SERVER-123507 Encrypted predicates inside a $vectorSearch prefilter should get replaced with encryption placeholders
SERVER-124183 Limit scope of authenticate
SERVER-124190 Forbid aggregate exchange field from non-internal clients
SERVER-123918 Validate runtimeConstants.userRoles in IDL
SERVER-123951 $_internalConvertBucketIndexStats should not return PauseExecution on failed index conversion
SERVER-124031 Ensure Exchange::getTargetConsumer correctly handles MaxKey
SERVER-123633 Fix handling of user $-prefixed fields colliding with internal metadata
SERVER-123370 LDAP query password is logged when set through setParameter
SERVER-123440 GeometryCollection with strict-winding polygon causes 2dsphere index key generation crash
SERVER-124959 Validate doc diff array bounds and $_internalApplyOplogUpdate BSON
All JIRA issues closed in 8.3.3
8.3.3 Changelog

8.3.2 - May 12, 2026

Important

MongoDB 8.3.2 contains a fix for CVE-2026-8053

For the latest information about MongoDB security updates, see MongoDB Security Bulletins.

Issues fixed:

SERVER-126021 Undefined behavior when inserting data with duplicate field names into timeseries collections
All JIRA issues closed in 8.3.2
8.3.2 Changelog

8.3.1 - May 4, 2026

Important

MongoDB 8.3.1 contains a fix for:

For the latest information about MongoDB security updates, see MongoDB Security Bulletins.

Issues fixed:

SERVER-121610 Ensure cached emit() calls are no-op
SERVER-121895 Improve redaction of validation errors
SERVER-124974 Ensure memory lifetime during $match pushdown analysis
All JIRA issues closed in 8.3.1
8.3.1 Changelog

8.3.0 - May 4, 2026

Important

MongoDB 8.3 includes fixes for CVE-2025-12893, CVE-2025-13507, CVE-2025-14345, and CVE-2026-8336, CVE-2026-9754.

For the latest information about MongoDB security updates, see MongoDB Security Bulletins.

General Changes

$scoreFusion Aggregation Stage is Generally Available

Starting in MongoDB 8.3, the $scoreFusion aggregation stage is generally available (GA). (The related $rankFusion aggregation stage is generally available starting in MongoDB 8.0.)

Accessing Array Element Indexes in $map, $filter, and $reduce

MongoDB 8.3 improves access to array element indexes in $map, $filter, and $reduce aggregation expressions. You can use the new arrayIndexAs field to set a variable to store the index of an array element. You can also use the new $$IDX aggregation system variable to access the index of the current array element if you omit arrayIndexAs.

FTDC Statistics

Starting in MongoDB 8.3, Full Time Diagnostic Data Capture (FTDC) collects connPoolStats metrics for mongod processes.

serverStatus Output

serverStatus includes the following new fields in its output:

MongoDB 8.3 removes the service field in the serverStatus output.

Starting in MongoDB 8.3, you can exclude all optional fields from the serverStatus output by specifying none: 1. After you exclude all optional fields, you can then specify the fields you want to include.

For details, see Exclude All Optional Fields.

You can also optionally specify lockContentionMetrics: 1 in the serverStatus command to include lockContentionMetrics in the output.

String Conversion Enhancements

Starting in MongoDB 8.3, $toString can convert additional BSON types to strings, including objects, arrays, regular expressions, MaxKeys, MinKeys, and timestamps. For details, see $toString.

MongoDB 8.3 introduces the optional base argument for $convert to convert between string and numeric values using bases 2, 8, 10, and 16. For details, see $convert.

Array Conversion Enhancements

Starting in MongoDB 8.3, you can convert strings that represent arrays using $convert or the shorthand expression $toArray.

You can also convert between binData and arrays of numeric values. For details, see Convert binData to Array and Convert an Array of Numeric Values to binData.

Object Conversion Enhancements

Starting in MongoDB 8.3, you can convert strings that represent objects using $convert or the shorthand expression $toObject.

Geospatial Index Generation

Starting in MongoDB 8.3, if a document contains both GeoJSON and legacy numeric coordinate fields, geospatial index generation prioritizes GeoJSON coordinates.

If your documents contain legacy numeric coordinate values that precede GeoJSON coordinates and existing indexes rely on that behavior, you might need to rebuild your geospatial indexes.

This change may require you to rebuild geospatial indexes if your documents contain legacy numeric coordinate values that precede GeoJSON coordinates and existing indexes rely on that behavior. Review geospatial queries to confirm they return expected results.

Remove Shard Changes

Starting in MongoDB 8.3, the removeShard command is deprecated. This release introduces four new commands to replace removeShard and provide granular control over the shard draining and removal process.

MongoDB provides four additional commands to transition from an embedded config server to a dedicated config server.

PreAuth Connection Limit Parameters

MongoDB 8.3 adds three new server parameters that limit the resource consumption of pre-auth connections:

cachePressureQueryPeriodMilliseconds Parameter

MongoDB 8.3 adds the cachePressureQueryPeriodMilliseconds parameter which sets the time interval MongoDB waits between checks for storage engine cache pressure. If the storage engine is under cache pressure, MongoDB aborts the oldest transaction. For details, see cachePressureQueryPeriodMilliseconds.

diagnosticDataCollectionDirectorySizeMB Parameter

MongoDB 8.3 increases the default value of diagnosticDataCollectionDirectorySizeMB from 200 to 500 MiB.

overloadAwareServerSelectionEnabled Parameter

MongoDB 8.3 adds the overloadAwareServerSelectionEnabled parameter, which controls whether retries that target other servers in the cluster avoid members that recently returned an error labeled SystemOverloadedError. You can enable this parameter to opt in to overload-aware retargeting.

ingressRequestRateLimiterApplicationExemptions Parameter

Starting in MongoDB 8.3, the ingressRequestRateLimiterApplicationExemptions parameter lets you specify applications to exempt from ingress request rate limiting. For details, see ingressRequestRateLimiterApplicationExemptions.

Database Profiler Parameters and Metrics

MongoDB 8.3 adds two parameters that let you control the impact that the Database Profiler has on query performance:

MongoDB 8.3 also adds two related serverStatus metrics:

Retry Parameters

MongoDB 8.3 adds parameters to configure how internal server-side clients (between mongos and mongod) back off when retrying operations that fail due to overload.

BSONObjectTooLarge Code for Upsert Errors

Starting in 8.3, upsert operations that produce a BSON object that is too large return the 10334 BSONObjectTooLarge error code. In earlier versions, upsert operations that produce a BSON object that is too large return the 17419 or 17420 error codes.

validate Command Updates

Starting in 8.3, MongoDB no longer automatically enables the checkBSONConformance field in the db.collection.validate() method when full is true. Additionally, the db.collection.validate() method now checks to ensure a collection doesn't have any documents that exceed 16 MB.

New Expression $subtype

MongoDB 8.3 introduces a new $subtype expression to extract the subtype of binary data objects.

New Expressions for Extended JSON Conversion

MongoDB 8.3 introduces new aggregation expressions for converting between BSON and Extended JSON (EJSON) format:

$serializeEJSON - Converts BSON values to Extended JSON format with type wrappers. Supports both Canonical and Relaxed Extended JSON formats.
$deserializeEJSON - Converts Extended JSON format back to native BSON values.

These expressions can be combined with $convert to parse JSON strings, transform Extended JSON values into native BSON values, and convert back to JSON format.

New Expression $createObjectId

Starting in MongoDB 8.3, you can use $createObjectId to generate new random ObjectId() values in pipelines and expression-based updates.

New Hashing Expressions

MongoDB 8.3 introduces two new aggregation expressions for generating hashes from UTF-8 strings or binary data:

$hash - Generates a BinData hash value from a UTF-8 string or binary data using MD5, SHA-256, or XXH64.
$hexHash - Generates an uppercase hexadecimal string hash from a UTF-8 string or binary data using MD5, SHA-256, or XXH64.

New $meta Keyword

MongoDB 8.3 introduces a new "searchRootDocumentId" keyword for the $meta expression. You can use this keyword to return the _id value of the root document for embedded documents in the $search result set. To learn more, see searchRootDocumentId.

Pre-Epoch Dates

Starting in MongoDB 8.3, if unit is not "millisecond" in $dateAdd or $dateSubtract and the input date is before ISODate("1970-01-01T00:00:00Z"), the result will be one second greater than in previous versions of MongoDB. This also affects the results of aggregations that perform time-based calculations like $setWindowFields and $densify.

Geospatial Index Generation

MongoDB 8.3, continues the behavior introduced in MongoDB 8.2. If a document contains both GeoJSON and legacy numeric coordinate fields, geospatial index generation prioritizes GeoJSON coordinates.

If your documents contain legacy numeric coordinate values that precede GeoJSON coordinates and existing indexes rely on that behavior, you might need to rebuild your geospatial indexes.

This change might require you to rebuild geospatial indexes if your documents contain legacy numeric coordinate values that precede GeoJSON coordinates and existing indexes rely on that behavior. Review geospatial queries to confirm they return expected results.

Subnormal Numbers in $convert Pipelines

Starting in MongoDB 8.3, the server is able to parse the full range of all representable double precision floating point numbers. This includes subnormal numbers where the most significant digit has leading zeroes and the exponent has the least possible value.

For details, see Subnormal Numbers.

chars Length Limit for $trim, $ltrim, and $rtrim

Starting in MongoDB 8.3, the length of the string you provide to chars is limited to 4096 characters. For details, see $trim Limitations.

Window Functions

Starting in MongoDB 8.3, you can use $mergeObjects in $setWindowFields operations.

sp.process() limit Option

Starting in MongoDB 8.3, sp.process() supports the options.limit input parameter. After sp.process() returns limit documents to your terminal, the session ends.

Text Search Spilling in Query Engine

Starting in MongoDB 8.3, the query engine limits the TextOr stage memory usage to 100 megabytes. The TextOr stage processes $text queries that read text score metadata. For example, TextOr processes queries that sort results by text score. If the TextOr stage exceeds this limit:

If allowDiskUse is true, the stage spills intermediate results to disk.
If allowDiskUse is false, the query fails with an exceeded memory limit error.

In earlier versions, the TextOr stage had no memory limit and consumed RAM without restrictions, risking out-of-memory (OOM) errors.

Representative Query Backfill for Query Settings

Starting in MongoDB 8.3, if the FCV is 8.3 or later, MongoDB backfills the representativeQuery field for query settings that you set with a query shape hash. When MongoDB runs a query that matches the query shape, it schedules the backfill. The backfill requires no action from you.

The backfill runs asynchronously on a best-effort basis to limit the performance impact on your queries. A query setting isn't guaranteed to be backfilled the first time a matching query runs. If a backfill doesn't complete, MongoDB attempts it again the next time a matching query runs.

To hold the additional representative queries, MongoDB 8.3 also increases the storage capacity for representative queries in query settings beyond the original 16 MB BSON document limit.

To learn how to set query settings with a query shape hash, see setQuerySettings.

Sharding

DDL Operations for Sharded Clusters Can Only Run on mongos

Starting in MongoDB 8.3, you can only run DDL operations and applyOps on a mongos for all sharded clusters. These operations may be temporarily unavailable while transitioning from a replica set to a sharded cluster.

findShardsOnConfigTimeoutMS Parameter

MongoDB 8.3 adds the findShardsOnConfigTimeoutMS parameter which sets the timeout in milliseconds for find operations against the config.shards namespace. For details, see findShardsOnConfigTimeoutMS.

config.csrs.indexes Removed

MongoDB 8.3 removes the config.csrs.indexes namespace.

2dsphereIndexVersion

Starting in MongoDB 8.3, 2dsphereIndexVersion is set to version 4 by default.

If you need to downgrade the FCV to anything below 8.3, you must first drop the 2dsphere version 4 indexes.

Shard Query Stats for mongos-Originated Queries

Starting in MongoDB 8.3, shard servers include queries that originate from mongos in their query statistics when queryStats is enabled. Previously, most queries forwarded from mongos to shards did not appear in shard-level query stats, which reduced the completeness of shard-level diagnostics.

Conversion to Sharded Clusters

Starting in MongoDB 8.3, replica sets that were previously sharded clusters cannot be converted back into sharded clusters.

The conversion of a sharded cluster into a replica set preserves sharding metadata from its prior deployment, including a shard identity document, which blocks it from again becoming a sharded cluster. If you attempt a self-managed conversion back into a sharded cluster, MongoDB returns an error.

To convert such replica sets into sharded clusters, contact Technical Support.

Conversion to Embedded Config Shard

MongoDB 8.3 introduces the mongod --replicaSetConfigShardMaintenanceMode option.

In previous releases, converting a replica set to a sharded cluster with an embedded config shard required you to first migrate to a sharded cluster with a dedicated config server replica set.

If you restart a replica set with the --replicaSetConfigShardMaintenanceMode and --configsvr options, you can convert the primary node directly into an embedded config shard.

For more information, see Convert Replica Set to an Embedded Config Shard.

Time Series

refineCollectionShardKey Formatting

Starting in MongoDB 8.3, refineCollectionShardKey for time-series collections only accepts shard keys specified using the collection's logical meta and time fields. MongoDB no longer supports specifying keys using the underlying buckets format.

Index Naming Restrictions

Starting in MongoDB 8.3, creating an index with the name of "_id_" or specifying a hint of "_id_" on time series collections returns an error.

timeField Naming Restrictions

Starting in MongoDB 8.3, you cannot create a timeField that starts with a $ character.

Logging

Fields to Track Use of Memory by Queries

Starting in MongoDB 8.3, you can use the following new fields to track query memory use:

Field	Description
`inUseTrackedMemBytes`	Number of bytes of tracked memory in use by the current query operation.
`peakTrackedMemBytes`	Maximum number of bytes of tracked memory in use by the current query operation.

Both fields appear in the following places:

The peakTrackedMemBytes field also appears in the following places:

Starting in 8.3, use the following new metrics in $queryStats to measure the behavior of checkForInterrupt:

metrics.numInterruptChecksPerSec
metrics.overdueInterruptApproxMaxMillis

Mongos Query Shape Field

Starting in MongoDB 8.3, slow query log entries have an optional originalQueryShapeHash field that contains that query shape of the following operations that originate on the mongos :

Slow In-Progress Query Logs

MongoDB 8.3 introduces slow in-progress query log entries. Log messages on slow in-progress queries contain less information than standard slow query logs. MongoDB logs queries at most once if the query's duration surpasses the slowOpInProgressThreshold. You can set the threshold with db.setProfilingLevel() or the new mongod --defaultSlowInProgMS command line option.

Explain Output

Sharded Clusters

Starting in MongoDB 8.3, if you run explain() against a database that does not exist on a sharded cluster, the execution stage reaches the end-of-stream and the operation does not create the database. For more information on end-of-stream execution stats, see explain.executionStats.executionStages.isEOF.

Security

SCRAM-SHA-1 and FIPS Mode

Starting in MongoDB 8.3, you cannot specify SCRAM-SHA-1 for authenticationMechanisms while also specifying mongod --tlsFIPSMode or mongos --tlsFIPSMode.

If you try to specify SCRAM-SHA-1 for authenticationMechanisms while also specifying --tlsFIPSMode, the server throws an error and logs a message similar to the following:

SCRAM-SHA-1 is not allowed in FIPS mode.

Changes Introduced in MongoDB 8.2

MongoDB 8.3 also includes changes introduced in MongoDB 8.2. This section describes changes that were introduced in MongoDB 8.2.

Performance Improvements

MongoDB 8.2 introduces performance improvements from MongoDB 8.1, including but not limited to:

Faster initial sync.
Faster time-series bulk insertions.
Reduced query multi-planning costs.

Note

The amount of performance improvement can vary depending on the configuration of your workloads and database instances.

Index Generation

Geospatial Index Generation

Starting in MongoDB 8.2, if a document contains both GeoJSON and legacy numeric coordinate fields, geospatial index generation prioritizes GeoJSON coordinates.

If your documents contain legacy numeric coordinate values that precede GeoJSON coordinates and existing indexes rely on that behavior, you might need to rebuild your geospatial indexes.

Sharding

terminateSecondaryReadsOnOrphanCleanup Parameter

MongoDB 8.2 adds the terminateSecondaryReadsOnOrphanCleanup parameter, which controls whether long-running read operations on secondary nodes automatically terminate before orphaned document deletion following a chunk migration.

By default, this parameter is set to true. If a read operation on a secondary node begins before the chunk migration commits, MongoDB automatically terminates the operation before deleting the orphaned documents. In MongoDB versions before 8.2, these operations continue executing after orphaned document deletion and may silently miss documents without returning an error.

To support this new behavior, the default value for orphanCleanupDelaySecs is now 3600 (previously 900).

General Changes

Index Builds During Initial Sync

Starting in MongoDB 8.2 (and 8.0.13, 7.0.26), index builds during initial sync use 10% of available RAM by default. You can specify a different percentage of memory for MongoDB to use with the initialSyncIndexBuildMemoryPercentage parameter.

By default, the amount of available memory must be between 200 MB and 16 GB, inclusive. You use the following parameters to specify different minimum and maximum thresholds for memory usage:

Query Statistics

Starting in MongoDB 8.2, the $queryStats output includes the following metrics on delinquent tickets:

metrics.delinquentAcquisitions
metrics.totalAcquisitionDelinquencyMillis
metrics.maxAcquisitionDelinquencyMillis

MongoDB considers an execution ticket as delinquent when acquisition takes too long.

WiredTiger Cache Size Configuration as a Percentage

Starting in MongoDB 8.2, you can configure the WiredTiger internal cache size using a new percentage-based option. In addition to the existing --wiredTigerCacheSizeGB and storage.wiredTiger.engineConfig.cacheSizeGB gigabyte-based settings, you can now specify the cache size as a percentage of the available memory with the --wiredTigerCacheSizePct and storage.wiredTiger.engineConfig.cacheSizePct options.

New Inconsistency Type: Range Deletion Missing Shard Key Index

Starting in MongoDB 8.2, a new inconsistency type RangeDeletionMissingShardKeyIndex is implemented. The inconsistency type indicates that a sharded collection exists that doesn't have an index compatible with the collection shard key and there is at least one remaining range deletion task to complete.

New Aggregation Expression

Starting in MongoDB 8.2, you can use $currentDate with aggregate() to return the current time on the server.

New $currentOp Field

The $currentOp aggregation stage now includes the versionContext field, which provides information on the Feature Compatibility Version (FCV) of the operation.

serverStatus Output Change

serverStatus includes the following new fields in its output:

Explain Output for Disk Spilling Stages

Starting in MongoDB 8.2, the Explain Results for stages that spill to disk now include standardized metrics under consistent field names. This update provides a more unified way to track disk usage for memory-intensive operations.

The new fields include:

Repair Mode Field in Validation Output

Starting in MongoDB 8.2, the validate command and the db.collection.validate() helper method return a new repairMode field that indicates what types of data inconsistencies the validate command attempted to repair, if detected.

Support for zstd Fast Compression

Starting in MongoDB 8.2, The storage.wiredTiger.engineConfig.zstdCompressionLevel setting supports negative values for fast zstd compression. Negative values provide faster compression and decompression speeds at the cost of the compression ratio. The new supported range is -7 to 22.

Targeted Mirrored Reads

Starting in MongoDB 8.2, you can selectively mirror read operations to specific servers that need their caches warmed up by tagging the nodes for read mirroring. Unlike general mirrored reads, targeted read mirroring allows you to target hidden nodes and mirror from both primary and secondary nodes.

You can configure targeted mirrored reads using the targetedMirroring field in the mirrorReads parameter.

Rate Limit Ingress Connection Establishment

Starting in MongoDB 8.2, you can enable rate limiting for ingress connections to preserve CPU resources during overload. When enabled, you can see when the rate of incoming connections exceeds the connection establishment rate they specified and configure parameters to specify how your MongoDB deployment handles excess connections.

You can configure rate limiting using the following new fields:

chars Length Limit for $trim, $ltrim, and $rtrim

Starting in MongoDB 8.2.8, the length of the string you provide to chars is limited to 4096 characters. For details, see $trim Limitations.

Security

Queryable Encryption Prefix, Suffix, and Substring Query Public Preview

Warning

Prefix, Suffix, and Substring Queries are in Public Preview

Queryable Encryption prefix, suffix, and substring queries are available in public preview in MongoDB 8.2. Do not enable these query types in production. Public preview functionality will be incompatible with the GA feature, and you will have to drop any collections that enable these queries.

MongoDB 8.2 lets you enable prefix, suffix, and substring queries on encrypted string fields in Queryable Encryption enabled collections. For details, see enable substring queries and Supported Aggregation Expressions.

To use the Public Preview prefix, suffix, or substring queries with mongosh, you must separately download the Automatic Encryption Shared Library 8.2 or later, then specify the library path to mongosh using the --cryptSharedLibPath option.

Known Issues

This section describes known issues in MongoDB 8.2 and their resolution status.

In Version	Issue	Status
8.2.4, 8.2.5	SERVER-118428: Changes to `mongocryptd` limit the maximum size of messages that `mongocryptd` can receive to 16 KiB. Users may encounter this issue when they send commands larger than 16 KiB through automatic Client-Side Field Level Encryption (CSFLE) or Queryable Encryption. To avoid this bug, skip these versions when you upgrade `mongocryptd` or use the crypt_shared library.	Unresolved.
8.2.0	SERVER-106469: The `mongocryptd`, `mongod`, and `mongos` processes do not start on Windows when launched with the `--logpath NUL` argument. A third-party dependency mistakenly disallows the use of NUL, resulting in this log file path preventing `mongocryptd` from starting. MongoDB drivers may fail to start `mongocryptd` successfully on Windows if `--logpath NUL` is specified. The MongoDB .NET/C# Driver uses `--logpath NUL` in its default configuration and will fail to start on Windows. You can avoid the .NET/C# driver `mongocryptd` issue in the following ways: Use the Automatic Encryption Shared Library instead of `mongocryptd`. Specify a non-NUL log file path when starting `mongocryptd`.	We are targeting a fix for this issue in MongoDB 8.2.1.
8.2.0	SERVER-109626: v8.2.0 introduces some change stream performance regressions. Applications relying on change streams for real-time data processing may experience up to a 15% performance degradation compared to v8.0.	Fixed in MongoDB 8.2.1. Upgrading to 8.2.1 restores the pre-8.2 change stream behavior for the `collectionUUID` and `updateDescription.disambiguatedPaths` fields and removes the performance regression.
8.2.0	SERVER-110250: Users running memory-intensive operations that require disk spilling can experience server crashes if the number of actively spilling queries exceeds `1000`. To mitigate this issue, raise the `spillWiredTigerSessionMax` `setParameter` value to a higher value.	We are targeting a fix for this issue in MongoDB 8.2.1.

Server Parameters

Starting in MongoDB 8.2, the following server parameters are available:

ShardingTaskExecutorPoolMaxQueueDepth

Upgrade Procedures

To upgrade to MongoDB 8.3, refer to the upgrade instructions specific to your MongoDB deployment:

If you need guidance on upgrading to 8.3, MongoDB professional services offer support to help ensure a smooth transition without interruption to your MongoDB application. To learn more, see MongoDB Consulting.

Download

To download MongoDB 8.3, go to the MongoDB Download Center.

Important

Minor releases may not support some features, including Atlas Live Migration or mongosync. If you require these features, use a Major release instead.

Downgrade Considerations

Starting in MongoDB 8.3, you can downgrade your MongoDB version to the immediately previous minor or major version.

Only Single-Version Downgrades are Supported

MongoDB supports single-version downgrades along adjacent versions only. You cannot downgrade to a release that is multiple versions behind your current release.

For any versions, major or minor, you can upgrade or downgrade to its adjacent neighbors. For example, you can downgrade from 8.3 to 8.2 or upgrade from 7.0 to 8.0.
For all versions, major or minor, you can downgrade to the immediately previous major version. For example, from 8.3 to 8.0.
For any minor version, you can upgrade to the immediately next version. For example, from 8.2 to 8.3.

Backward-Incompatible Features

MongoDB 8.3 includes features that are not compatible with earlier releases. Downgrading from 8.3 to an earlier release requires that you remove data that uses these features.

For more information, see Backward-Incompatible Features.

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Server Release Notes

Compatibility Changes