Troubleshooting Amazon OpenSearch Service - Amazon OpenSearch Service (successor to Amazon Elasticsearch Service)

Troubleshooting Amazon OpenSearch Service

This topic describes how to identify and solve common Amazon OpenSearch Service issues. Consult the information in this section before contacting AWS Support.

Can't access OpenSearch Dashboards

The OpenSearch Dashboards endpoint doesn't support signed requests. If the access control policy for your domain only grants access to certain IAM users or roles and you haven't configured Amazon Cognito authentication, you might receive the following error when you attempt to access Dashboards:

"User: anonymous is not authorized to perform: es:ESHttpGet"

If your OpenSearch Service domain uses VPC access, you might not receive this error, but the request might time out. To learn more about correcting this issue and the various configuration options available to you, see Controlling access to OpenSearch Dashboards, About access policies on VPC domains, and Identity and Access Management in Amazon OpenSearch Service.

Can't access VPC domain

See About access policies on VPC domains and Testing VPC domains.

Cluster in read-only state

Compared to earlier Elasticsearch versions, OpenSearch and Elasticsearch 7.x use a different system for cluster coordination. In this new system, when the cluster loses quorum, the cluster is unavailable until you take action. Loss of quorum can take two forms:

  • If your cluster uses dedicated master nodes, quorum loss occurs when half or more are unavailable.

  • If your cluster does not use dedicated master nodes, quorum loss occurs when half or more of your data nodes are unavailable.

If quorum loss occurs and your cluster has more than one node, OpenSearch Service restores quorum and places the cluster into a read-only state. You have two options:

If you prefer to use the cluster as-is, verify that cluster health is green using the following request:

GET _cat/health?v

If cluster health is red, we recommend restoring the cluster from a snapshot. You can also see Red cluster status for troubleshooting steps. If cluster health is green, check that all expected indices are present using the following request:

GET _cat/indices?v

Then run some searches to verify that the expected data is present. If it is, you can remove the read-only state using the following request:

PUT _cluster/settings { "persistent": { "cluster.blocks.read_only": false } }

If quorum loss occurs and your cluster has only one node, OpenSearch Service replaces the node and does not place the cluster into a read-only state. Otherwise, your options are the same: use the cluster as-is or restore from a snapshot.

In both situations, OpenSearch Service sends two events to your AWS Personal Health Dashboard. The first informs you of the loss of quorum. The second occurs after OpenSearch Service successfully restores quorum. For more information about using the AWS Personal Health Dashboard, see the AWS Health User Guide.

Red cluster status

A red cluster status means that at least one primary shard and its replicas are not allocated to a node. OpenSearch Service keeps trying to take automated snapshots of all indices regardless of their status, but the snapshots fail while the red cluster status persists.

The most common causes of a red cluster status are failed cluster nodes and the OpenSearch process crashing due to a continuous heavy processing load.


OpenSearch Service stores automated snapshots for 14 days regardless of the cluster status. Therefore, if the red cluster status persists for more than two weeks, the last healthy automated snapshot will be deleted and you could permanently lose your cluster's data. If your OpenSearch Service domain enters a red cluster status, AWS Support might contact you to ask whether you want to address the problem yourself or you want the support team to assist. You can set a CloudWatch alarm to notify you when a red cluster status occurs.

Ultimately, red shards cause red clusters, and red indices cause red shards. To identity the indices causing the red cluster status, OpenSearch has some helpful APIs.

  • GET /_cluster/allocation/explain chooses the first unassigned shard that it finds and explains why it cannot be allocated to a node:

    { "index": "test4", "shard": 0, "primary": true, "current_state": "unassigned", "can_allocate": "no", "allocate_explanation": "cannot allocate because allocation is not permitted to any of the nodes" }
  • GET /_cat/indices?v shows the health status, number of documents, and disk usage for each index:

    health status index uuid pri rep docs.count docs.deleted store.size green open test1 30h1EiMvS5uAFr2t5CEVoQ 5 0 820 0 14mb 14mb green open test2 sdIxs_WDT56afFGu5KPbFQ 1 0 0 0 233b 233b green open test3 GGRZp_TBRZuSaZpAGk2pmw 1 1 2 0 14.7kb 7.3kb red open test4 BJxfAErbTtu5HBjIXJV_7A 1 0 green open test5 _8C6MIXOSxCqVYicH3jsEA 1 0 7 0 24.3kb 24.3kb

Deleting red indices is the fastest way to fix a red cluster status. Depending on the reason for the red cluster status, you might then scale your OpenSearch Service domain to use larger instance types, more instances, or more EBS-based storage and try to recreate the problematic indices.

If deleting a problematic index isn't feasible, you can restore a snapshot, delete documents from the index, change the index settings, reduce the number of replicas, or delete other indices to free up disk space. The important step is to resolve the red cluster status before reconfiguring your OpenSearch Service domain. Reconfiguring a domain with a red cluster status can compound the problem and lead to the domain being stuck in a configuration state of Processing until you resolve the status.

Recovering from a continuous heavy processing load

To determine if a red cluster status is due to a continuous heavy processing load on a data node, monitor the following cluster metrics.

Relevant metric Description Recovery

Specifies the percentage of the Java heap used for all data nodes in a cluster. View the Maximum statistic for this metric, and look for smaller and smaller drops in memory pressure as the Java garbage collector fails to reclaim sufficient memory. This pattern likely is due to complex queries or large data fields.

x86 instance types use the Concurrent Mark Sweep (CMS) garbage collector, which runs alongside application threads to keep pauses short. If CMS is unable to reclaim enough memory during its normal collections, it triggers a full garbage collection, which can lead to long application pauses and impact cluster stability.

ARM-based Graviton instance types use the Garbage-First (G1) garbage collector, which is similar to CMS, but uses additional short pauses and heap defragmentation to further reduce the need for full garbage collections.

In either case, if memory usage continues to grow beyond what the garbage collector can reclaim during full garbage collections, OpenSearch crashes with an out of memory error. On all instance types, a good rule of thumb is to keep usage below 80%.

The _nodes/stats/jvm API offers a useful summary of JVM statistics, memory pool usage, and garbage collection information:

GET domain-endpoint/_nodes/stats/jvm?pretty

Set memory circuit breakers for the JVM. For more information, see JVM OutOfMemoryError.

If the problem persists, delete unnecessary indices, reduce the number or complexity of requests to the domain, add instances, or use larger instance types.

CPUUtilization Specifies the percentage of CPU resources used for data nodes in a cluster. View the Maximum statistic for this metric, and look for a continuous pattern of high usage. Add data nodes or increase the size of the instance types of existing data nodes.
Nodes Specifies the number of nodes in a cluster. View the Minimum statistic for this metric. This value fluctuates when the service deploys a new fleet of instances for a cluster. Add data nodes.

Yellow cluster status

A yellow cluster status means the primary shards for all indices are allocated to nodes in a cluster, but the replica shards for at least one index aren't. Single-node clusters always initialize with a yellow cluster status because there's no other node to which OpenSearch Service can assign a replica. To achieve green cluster status, increase your node count. For more information, see Sizing Amazon OpenSearch Service domains.

Multi-node clusters might briefly have a yellow cluster status after creating a new index or after a node failure. This status self-resolves as OpenSearch replicates data across the cluster. Lack of disk space can also cause yellow cluster status; the cluster can only distribute replica shards if nodes have the disk space to accommodate them.


You might receive a ClusterBlockException error for the following reasons.

Lack of available storage space

If no nodes have enough storage space to accommodate shard relocation, basic write operations like adding documents and creating indices can start to fail. Calculating storage requirements provides a summary of how OpenSearch Service uses disk space.

To avoid issues, monitor the FreeStorageSpace metric in the OpenSearch Service console and create CloudWatch alarms to trigger when FreeStorageSpace drops below a certain threshold. GET /_cat/allocation?v also provides a useful summary of shard allocation and disk usage. To resolve issues associated with a lack of storage space, scale your OpenSearch Service domain to use larger instance types, more instances, or more EBS-based storage.

Blocked disks due to low memory

When the JVMMemoryPressure metric exceeds 92% for 30 minutes, OpenSearch Service triggers a protection mechanism and blocks all write operations to prevent the cluster from reaching red status. When the protection is on, write operations fail with a ClusterBlockException error, new indices can't be created, and the IndexCreateBlockException error is thrown.

When the JVMMemoryPressure metric returns to 88% or lower for five minutes, the protection is disabled, and write operations to the cluster are unblocked.

JVM OutOfMemoryError

A JVM OutOfMemoryError typically means that one of the following JVM circuit breakers was reached.

Circuit breaker Description Cluster setting property
Parent Breaker Total percentage of JVM heap memory allowed for all circuit breakers. The default value is 95%.
Field Data Breaker Percentage of JVM heap memory allowed to load a single data field into memory. The default value is 40%. If you upload data with large fields, you might need to raise this limit. indices.breaker.fielddata.limit
Request Breaker Percentage of JVM heap memory allowed for data structures used to respond to a service request. The default value is 60%. If your service requests involve calculating aggregations, you might need to raise this limit. indices.breaker.request.limit

Failed cluster nodes

Amazon EC2 instances might experience unexpected terminations and restarts. Typically, OpenSearch Service restarts the nodes for you. However, it's possible for one or more nodes in an OpenSearch cluster to remain in a failed condition.

To check for this condition, open your domain dashboard on the OpenSearch Service console. Go to the Cluster health tab and find the Total nodes metric. See if the reported number of nodes is fewer than the number that you configured for your cluster. If the metric shows that one or more nodes is down for more than one day, contact AWS Support.

You can also set a CloudWatch alarm to notify you when this issue occurs.


The Total nodes metric is not accurate during changes to your cluster configuration and during routine maintenance for the service. This behavior is expected. The metric will report the correct number of cluster nodes soon. To learn more, see Making configuration changes in Amazon OpenSearch Service.

To protect your clusters from unexpected node terminations and restarts, create at least one replica for each index in your OpenSearch Service domain.

Exceeded maximum shard limit

OpenSearch as well as 7.x versions of Elasticsearch have a default setting of no more than 1,000 shards per node. OpenSearch/Elasticsearch throw an error if a request, such as creating a new index, would cause you to exceed this limit. If you encounter this error, you have several options:

  • Add more data nodes to the cluster.

  • Increase the _cluster/settings/cluster.max_shards_per_node setting.

  • Use the _shrink API to reduce the number of shards on the node.

Can't enable audit logs

You might encounter the following error when you try to enable audit log publishing using the OpenSearch Service console:

The Resource Access Policy specified for the CloudWatch Logs log group does not grant sufficient permissions for Amazon OpenSearch Service to create a log stream. Please check the Resource Access Policy.

If you encounter this error, verify that the resource element of your policy includes the correct log group ARN. If it does, take the following steps:

  1. Wait several minutes.

  2. Refresh the page in your web browser.

  3. Choose Select existing group.

  4. For Existing log group, choose the log group that you created before receiving the error message.

  5. In the access policy section, choose Select existing policy.

  6. For Existing policy, choose the policy that you created before receiving the error message.

  7. Choose Enable.

If the error persists after repeating the process several times, contact AWS Support.

Can't close index

OpenSearch Service supports the _close API only for OpenSearch and Elasticsearch versions 7.4 and later. If you're using an older version and are restoring an index from a snapshot, you can delete the existing index (before or after reindexing it). The other option is to use the rename_pattern and rename_replacement fields to rename the index as you restore it:

POST /_snapshot/my-repository/my-snapshot/_restore { "indices": "my-index-1,myindex-2", "include_global_state": true, "rename_pattern": "my-index-(\\d)", "rename_replacement": "restored-my-index-$1" }

If you plan to reindex, shrink, or split an index, you likely want to stop writing to it before performing the operation.

Mapper parsing exception while indexing

Elasticsearch 7.10 deprecated the following parameters for use within dynamic templates: coerce, dynamic, ignore_malformed, normalizer, null_values, omit_norms, and properties.

If you add a document to an index with a dynamic template that contains a deprecated parameter, you get the following error:

"error" : { "root_cause" : [ { "type" : "mapper_parsing_exception", "reason" : "unknown parameter [ignore_malformed] on mapper [mykeyword] of type [text]" } ] }

If you encounter this error, remove the deprecated parameter from your template and retry the request.

Client license checks

The default distributions of Logstash and Beats include a proprietary license check and fail to connect to the open source version of OpenSearch. Make sure you use the Apache 2.0 (OSS) distributions of these clients with OpenSearch Service.

Request throttling

If you receive persistent 403 Request throttled due to too many requests or 429 Too Many Requests errors, consider scaling vertically. Amazon OpenSearch Service throttles requests if the payload would cause memory usage to exceed the maximum size of the Java heap.

Can't SSH into node

You can't use SSH to access any of the nodes in your OpenSearch cluster, and you can't directly modify opensearch.yml. Instead, use the console, AWS CLI, or SDKs to configure your domain. You can specify a few cluster-level settings using the OpenSearch REST APIs, as well. To learn more, see Configuration API reference for Amazon OpenSearch Service and Supported operations.

If you need more insight into the performance of the cluster, you can publish error logs and slow logs to CloudWatch.

"Not Valid for the Object's Storage Class" snapshot error

OpenSearch Service snapshots do not support the S3 Glacier storage class. You might encounter this error when you attempt to list snapshots if your S3 bucket includes a lifecycle rule that transitions objects to the S3 Glacier storage class.

If you need to restore a snapshot from the bucket, restore the objects from S3 Glacier, copy the objects to a new bucket, and register the new bucket as a snapshot repository.

Invalid host header

OpenSearch Service requires that clients specify Host in the request headers. A valid Host value is the domain endpoint without https://, such as:


If you receive an Invalid Host Header error when making a request, check that your client or proxy includes the OpenSearch Service domain endpoint (and not, for example, its IP address) in the Host header.

Invalid M3 instance type

OpenSearch Service doesn't support adding or modifying M3 instances to existing domains running OpenSearch or Elasticsearch versions 6.7 and later. You can continue to use M3 instances with Elasticsearch 6.5 and earlier.

We recommend choosing a newer instance type. For domains running OpenSearch or Elasticsearch 6.7 or later, the following restriction apply:

  • If your existing domain does not use M3 instances, you can no longer change to them.

  • If you change an existing domain from an M3 instance type to another instance type, you can't switch back.

Hot queries stop working after enabling UltraWarm

When you enable UltraWarm on a domain, if there are no preexisting overrides to the search.max_buckets setting, OpenSearch Service automatically sets the value to 10000 to prevent memory-heavy queries from saturating warm nodes. If your hot queries are using more than 10,000 buckets, they might stop working when you enable UltraWarm.

Because you can't modify this setting due to the managed nature of Amazon OpenSearch Service, you need to open a support case to increase the limit. Limit increases don't require a premium support subscription.

Can't downgrade after upgrade

In-place upgrades are irreversible, but if you contact AWS Support, they can help you restore the automatic, pre-upgrade snapshot on a new domain. For example, if you upgrade a domain from Elasticsearch 5.6 to 6.4, AWS Support can help you restore the pre-upgrade snapshot on a new Elasticsearch 5.6 domain. If you took a manual snapshot of the original domain, you can perform that step yourself.

Need summary of domains for all AWS Regions

The following script uses the Amazon EC2 describe-regions AWS CLI command to create a list of all Regions in which OpenSearch Service could be available. Then it calls list-domain-names for each Region:

for region in `aws ec2 describe-regions --output text | cut -f4` do echo "\nListing domains in region '$region':" aws opensearch list-domain-names --region $region --query 'DomainNames' done

You receive the following output for each Region:

Listing domains in region:'us-west-2'... [ { "DomainName": "sample-domain" } ]

Regions in which OpenSearch Service is not available return "Could not connect to the endpoint URL."

Browser error when using OpenSearch Dashboards

Your browser wraps service error messages in HTTP response objects when you use Dashboards to view data in your OpenSearch Service domain. You can use developer tools commonly available in web browsers, such as Developer Mode in Chrome, to view the underlying service errors and assist your debugging efforts.

To view service errors in Chrome

  1. From the Chrome top menu bar, choose View, Developer, Developer Tools.

  2. Choose the Network tab.

  3. In the Status column, choose any HTTP session with a status of 500.

To view service errors in Firefox

  1. From the menu, choose Tools, Web Developer, Network.

  2. Choose any HTTP session with a status of 500.

  3. Choose the Response tab to view the service response.

Unauthorized operation after selecting VPC access

When you create a new domain using the OpenSearch Service console, you have the option to select VPC or public access. If you select VPC access, OpenSearch Service queries for VPC information and fails if you don't have the proper permissions:

You are not authorized to perform this operation. (Service: AmazonEC2; Status Code: 403; Error Code: UnauthorizedOperation

To enable this query, you must have access to the ec2:DescribeVpcs, ec2:DescribeSubnets, and ec2:DescribeSecurityGroups operations. This requirement is only for the console. If you use the AWS CLI to create and configure a domain with a VPC endpoint, you don't need access to those operations.

Stuck at loading after creating VPC domain

After creating a new domain that uses VPC access, the domain's Configuration state might never progress beyond Loading. If this issue occurs, you likely have AWS Security Token Service (AWS STS) disabled for your Region.

To add VPC endpoints to your VPC, OpenSearch Service needs to assume the AWSServiceRoleForAmazonOpenSearchService role. Thus, AWS STS must be enabled to create new domains that use VPC access in a given Region. To learn more about enabling and disabling AWS STS, see the IAM User Guide.

Can't connect from Alpine Linux

Alpine Linux limits DNS response size to 512 bytes. If you try to connect to your OpenSearch Service domain from Alpine Linux, DNS resolution can fail if the domain is in a VPC and has more than 20 nodes. If your domain is in a VPC, we recommend using other Linux distributions, such as Debian, Ubuntu, CentOS, Red Hat Enterprise Linux, or Amazon Linux 2, to connect to it.

Certificate error when using SDK

Because AWS SDKs use the CA certificates from your computer, changes to the certificates on the AWS servers can cause connection failures when you attempt to use an SDK. Error messages vary, but typically contain the following text:

Failed to query OpenSearch ... SSL3_GET_SERVER_CERTIFICATE:certificate verify failed

You can prevent these failures by keeping your computer's CA certificates and operating system up-to-date. If you encounter this issue in a corporate environment and do not manage your own computer, you might need to ask an administrator to assist with the update process.

The following list shows minimum operating system and Java versions:

  • Microsoft Windows versions that have updates from January 2005 or later installed contain at least one of the required CAs in their trust list.

  • Mac OS X 10.4 with Java for Mac OS X 10.4 Release 5 (February 2007), Mac OS X 10.5 (October 2007), and later versions contain at least one of the required CAs in their trust list.

  • Red Hat Enterprise Linux 5 (March 2007), 6, and 7 and CentOS 5, 6, and 7 all contain at least one of the required CAs in their default trusted CA list.

  • Java 1.4.2_12 (May 2006), 5 Update 2 (March 2005), and all later versions, including Java 6 (December 2006), 7, and 8, contain at least one of the required CAs in their default trusted CA list.

The three certificate authorities are:

  • Amazon Root CA 1

  • Starfield Services Root Certificate Authority - G2

  • Starfield Class 2 Certification Authority

Root certificates from the first two authorities are available from Amazon Trust Services, but keeping your computer up-to-date is the more straightforward solution. To learn more about ACM-provided certificates, see AWS Certificate Manager FAQs.


Currently, OpenSearch Service domains in the us-east-1 Region use certificates from a different authority. We plan to update the Region to use these new certificate authorities in the near future.