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Release Notes


    Couchbase Server 5.1.x fortifies the 5.x series to improve reliability, stability, and security of the product. Take a look at What’s new for a list of new features and improvements that are available in the 5.1.x series.

    Release 5.1.3

    Couchbase Server 5.1.3 was released in November 2018. This is the third maintenance release in the 5.1.x series of Couchbase Server and includes bug fixes to the data and index services, XDCR, and tools components.

    Note that upgrade from version 5.1.3 to version 6.0.0 is not supported. If you choose to upgrade to the 6.x series, then the supported upgrade path is from version 5.1.3 to version 6.0.1 or higher, after the newer versions are available.

    Fixed Issues

    Listed below are the notable fixes in this release.

    Cross Datacenter Replication (XDCR)

    Issue Description


    Improve XDCR connection management to prevent XDCR replication getting stuck while creating a checkpoint.

    Data Service

    Issue Description


    When data corruption is detected on a data service node, relevant information that can help troubleshoot is now being logged.


    When bucket memory usage exceeded the high watermark and reached 99% of the bucket quota, a race condition in KV-Engine DCP consumer was exposed, resulting in DCP messages being processed out-of-order.


    Fixed an issue where appending to a document reset the expiration value to 0, disabling TTL expiry.


    Fetching a random key from the Data service may hang if the bucket contains zero documents.

    Index Service

    Issue Description


    Document mutations with numbers greater than MaxInt64 encountered an error and were not indexed instead of being indexed with loss of precision.


    Issue Description


    The cbbackupmgr utility would hang and not return an error when trying to backup a cluster in which at least one node was down and had not failed over.

    Release 5.1.2

    Couchbase Server 5.1.2 was released in September 2018. This is the second maintenance release in the 5.1.x series of Couchbase Server and includes bug fixes to the storage, secondary indexing, query, and installer components.

    Fixed Issues

    Listed below are the notable fixes in this release. The complete list of issues fixed in this release is available here.

    Index Service

    Issue Description


    If the memory usage of the index nodes is close to quota, during rebalance, some of the index replicas may not get repaired when an index node is rebalanced out of the cluster. In release 5.1.2, the replicas will always be repaired. This issue is applicable only for the standard secondary storage mode.


    In previous releases, the automatic upgrade from ForestDB to Plasma storage lead to the restart of the index service when the last node was upgraded. This caused the unavailability of indexes during the warmup phase. This issue has fixed in this release, and the index service restart and the subsequent index unavailability is no longer observed during storage upgrade.


    The authentication requests from projector to Memcached now have a fixed timeout to avoid infinite wait time.


    In previous releases, the memory consumption of the index service could exceed the index service’s RAM quota setting. This caused problems when the quota was set to an amount that was close to the physical RAM on the Server node, for example this could lead to an out of memory error. This issue has been fixed.


    The initial index build has been optimized by reducing the storage operations during the initial build.


    The secondary index rebalance now builds indexes in smaller batches, in sequence. The default number of indexes per batch is set to 3 and the batching does not follow any specific criteria. The rebalance operation will randomly batch together 3 indexes for the build.


    The robustness of an index rebalance operation when vBuckets are moving around has been improved.


    Fixed an issue where the index service could crash when trying to index a large composite array index key due to buffer overflow.


    Issue Description


    Uninstalling Couchbase Server on a Debian-based systemd distribution such as Ubuntu 16 using apt-get remove and then running systemctl status couchbase-server reported that the service still exists but is "masked". This means the service was explicitly disabled in such a way that it could not be started, automatically or by hand. As a result, subsequent installations of any version of Couchbase Server failed as the service was rendered unstartable.


    Issue Description


    An empty array in the index scan caused incorrect results. This was observed when the scan_cap parameter was set to a small number (say 2) and thus, backfill was used.

    Release 5.1.1

    Couchbase Server 5.1.1 was released in June 2018. This is the first maintenance release in the 5.1.x series of Couchbase Server and includes important bug fixes applicable to all prior 5.x releases. We recommend that you upgrade to the 5.1.1 release and deploy these important bug fixes.

    Upgrading to Version 5.1.1

    Since most Couchbase Server upgrade procedures involve rebalance, some care must be taken when upgrading from a version prior to 5.1.1 to avoid being affected by MB-29959. Specifically, graceful failover and/or remove+rebalance should not be used to start this upgrade. As such, there are a few best practice approaches:

    1. Add a net-new node of at least 5.1.1 to any existing cluster first. This new node will become the orchestrator and any further rebalance will not be affected. From then on, follow the instructions in Performing an Online Upgrade.

    2. If a net-new node is not available, a hard failover can be performed on any node, that node upgraded to 5.1.1 and then re-added to the cluster. This is only required for the first node and, as per #1 above, any further rebalance operations will not be affected. From then on, follow the instructions in Performing an Online Upgrade.

    3. As XDCR is not affected by MB-29959, upgrading one cluster in a multi-cluster setup is also supported. Ensure that no writes are going to the cluster during its upgrade unless following the approaches listed in #1 or #2 above. For instructions, see Upgrade Using Inter-cluster Replication.

    4. Offline upgrade will not be affected. For instructions, see Performing the Offline Upgrade.

    Which method is best for your cluster will depend on your architecture and organization’s requirements (for example, SLAs, extra hardware/cluster availability, and so on). Once a cluster is upgraded to 5.1.1 or later, this guidance no longer applies and any supported upgrade method may be used going forward.

    Fixed Issues

    Cross Datacenter Replication (XDCR)

    Issue Description


    Fixed an issue where bidirectional XDCR across clusters was not working as expected.

    Data Service

    Issue Description


    During rebalance, it was observed that sometimes in-flight mutations did not persist correctly. We’ve fixed the issue in this release and recommend upgrading to get the fix.

    For best approaches when upgrading, see Upgrading to Version 5.1.1.

    Index Service

    Issue Description


    Upon upgrading a single node cluster from 4.5.1 to 5.1.0, the ForestDB indexes are upgraded to Plasma. However, after performing a rebalance, the Index Storage Mode list on the Web Console Settings page incorrectly displays the "Legacy Global Secondary" option.


    Issue Description


    The activity of query nodes was affected after a data node failover due to network outage. The query nodes can take 2-5mins to recover. If you want the query nodes to recover earlier, you must update the query timeout parameter to less than the default 2 mins.


    Fixed an issue where query nodes panic whenever the right side of LIKE clause was dependent on a field.


    Fixed an issue where the array indexing plan incorrectly included filter covers.

    Release 5.1.0

    Couchbase Server 5.1.0 was released in February 2018. In addition to bug fixes, this release includes enhancements to certificate-based authentication and the cbbackupmgr utility. The following sections list the fixed issues, known issues, and deprecated items in this release.

    Major Changes from Version 5.0

    • Support for Debian 9 has been added.

    • Certificate-based authentication now supports multiple prefixes.

    Known Issues

    Issue Description


    The query service does not support http/2 protocol. Consequently, if you want to use CURL, you must pass "--http1.1" as one of the parameters when using CURL to execute the query via the REST API.

    Fixed Issues

    Cross Datacenter Replication (XDCR)

    Issue Description


    Whenever simultaneous replications were set up using XDCR, it was observed that data was not replicated via the second replication stream. This was basically due to rules enforced to manage the execution of simultaneous mutations to the document.


    When the source node was upgraded in a unidirectional replication from 4.1 to 5.x, the GoGC global setting was set to 0 instead of a higher number.

    Data Service

    Issue Description


    Statistics for non-resident documents could be incorrect when operating on documents which contained system XATTRs.

    When using Couchbase Server 5.0 with Sync Gateway 1.5+ and the Mobile Convergence feature was enabled in Sync Gateway (enable_extended_attributes), the count of documents which are not resident could be under-reported in the UI.


    Rebalance failed initially if the destination node for a vBucket required a rollback.

    During a rebalance, if the destination node for a particular vBucket already had a previous, outdated version of that vBucket then the rebalance failed initially.


    If a document contained Extended Attributes and a Key/Value mutation request changed one of those XATTRs, the previous XATTR values were written to in a non-atomic way. This means that there was a potential race if another concurrent request was also accessing the same document at the same time - the other request could read a partial or corrupted value for the document.


    The data service incorrectly returned TEMP_FAIL for locked keys instead of ERROR_LOCKED.


    A backup resume operation on ephemeral buckets failed if there had been a data rollback during the previous backup that failed.

    Index Service

    Issue Description


    Rebalancing the index nodes failed with a timeout when the planner took a long time to execute.

    Query Service

    Issue Description


    On Windows platform, pasting a 1000+ character query into the cbq shell resulted in a partial query being pasted. This issue was observed after the query had been pasted a few times (>3).


    The ORDER BY operator sometimes continued to sort even after the operation was stopped leading to an exception.

    Search Service

    Issue Description


    Deleting FTS indexes during a rebalance operation may have produced a rare situation that resulted in an unbreakable loop with log message: " rebalance: waitAssignPIndexDone, awaiting a stats sample grab for pindex "


    Issue Description


    The cbbackup utility corrupted documents with extended attributes(XATTRs).


    The cbbackupmgr utility failed to backup directly from couchstore-files when the bucket was created on a version prior to 4.6 and threw the following error: “error: could not read couchstore file due to unsupported file format version; exception: unpack requires a string argument of length 18

    MB-27270, MB-27279

    Couchbase Server version 5.0 introduced a new storage system “plasma” available only in the Enterprise Edition. When using the Enterprise Edition, you had a choice of “plasma” or “forestDB” for storage and the default was set to “plasma”. Since “plasma” storage was not available in the Community Edition, no storage was allocated when other services were started. This has been fixed and the default storage in the Community Edition now points to ForestDB.


    A backup resume on ephemeral buckets failed if there had been a data rollback during the prior backup that failed.

    Web Console

    Issue Description


    When creating more than 10 views, the confirmation dialog informing you of the performance impact was not clickable. This has been fixed and the dialog is now clickable.


    From the Query Monitoring tab, sorting the completed requests on the “run at” column did not appear to work as expected. This was because the “run at” column did not display the date, making the result of the sorting operation appear incorrect, since the same time on two different dates would appear in different spots on the list. This has been fixed by adding a clickable tooltip to the “run at” time which displays the complete time including the date.


    The Query Workbench incorrectly displayed a warning for a valid index creation statement. This was due to an incorrect handling of the 'bind' expression by the client-side parser.

    New Supported Platforms

    This release adds support for the following platforms:

    • Debian 9

    • macOS 10.13 (High Sierra)

    See Supported Platforms for the complete list of supported platforms.

    Deprecated Features and Platforms

    Starting with this release, the following platforms are no longer supported:

    • Debian 7

    See Supported Platforms for the complete list of supported platforms.

    Release Notes for Older 5.x Versions