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Release Notes for Couchbase Server 5.5.x

Couchbase Server 5.5.x is a significant update of the Couchbase Data Platform. This release specifically highlights agility, performance, and manageability and includes enhancements to existing services as well as new server and SDK components.

Take a look at What’s New? for a list of new features and improvements that are available in this release.

Release 5.5.2

Couchbase Server 5.5.2, released in October 2018, is the second maintenance release in the 5.5.x series for Couchbase Server. This maintenance release includes fixes to the index and query services, XDCR, and installer components.

Fixed Issues

Cross Datacenter Replication (XDCR)

Issue Description


Fixed an issue where replication from version 4.5.x to version 5.5.x caused corruption on deleted documents leading to inability to rebalance.

Index Service

Issue Description


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.


After a rebalance, the index service was stuck waiting for Memcached. This has been fixed by adding a timeout mechanism so the index service does not hang.


Fixed an issue where the index service threw an error if an index was dropped when index mutation was ongoing.


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

Install and Upgrade

Issue Description


Fixed an issue where in-place (offline) upgrades to Couchbase Server on Windows from 5.0.x or 5.1.x to later releases failed.

Query Service

Issue Description


A race condition was observed when deleting a system bucket if the bucket was in use by a system bucket scan. This is a rare condition where the wrong unlock was used when the scan resumed after the delete operation completed.


When establishing connections, the cbq-engine would hang if the data node did not respond when trying to establish a handshake packet exchange with the data node. This has been fixed and the cbq-engine now throws an error if the connection cannot be established.


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.


Fixed an issue where an empty array from index scan did not work as expected when backfill was used.

Release 5.5.1

Couchbase Server 5.5.1, released in August 2018, is the first maintenance release in the 5.5.x series for Couchbase Server.

Fixed Issues

Data Service

Issue Description


Fixed an issue where the logs collected from the UI did not use the same salt across all nodes even though they were collected at the same time.


Fixed an issue where the Memcached process was unable to start if IPv6 protocol stack was disabled.

Index Service

Issue Description


During warmup, one of the indexes with low number of items triggered an issue and caused the internal garbage collector to run forever. Thus causing the entire index service to stall during warmup. This issue was observed when using Plasma storage engine.


Fixed an issue where the index service crashed with a "slice bounds out of range" error.


Fixed an issue where upgrading from 4.x to 5.x version of Couchbase Server caused an outage for GSI standard indexes. This was observed during rolling upgrade from ForestDB to Plasma. When the last ForestDB index service node was taken out of the cluster, the cluster compatibility mode changed to Plasma and the index service restarted.


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.

Tools, Web Console (UI) and REST API

Issue Description


Fixed an issue where an unexpected token error was seen when accessing the Web Console in Couchbase Server version 5.5.0.


Fixed an issue where the warning message on the Web Console showed an incorrect flag for the removal of dedicated bucket port as --remove-port instead of --remove-bucket-port.

Release 5.5.0

Couchbase Server 5.5.0 was released in July 2018.

Major Behavior Changes

Issue Description


The default number of Data Service worker threads has been increased; from 3/4 of the number of available CPU threads, to 7/8 of the number of available CPU threads (minimum of 4 in both cases). This makes better use of the available CPU resource, particularly on larger systems, as such users may see an increase in CPU utilization on such systems.


The permissions assigned to the cluster_admin role have been downgraded. As a result, The cluster_admin role no longer has FTS write permissions used to create FTS searches.

Workaround: Add the fts_admin role as required.


Prior to 5.5, the mctimings command defined the request start as the time when the 24 byte request header had been read by the Data Service. However, many requests contain a body which also needs to be read before a request can be processed. As such, the reported duration didn’t accurately reflect how long the server actually spent processing a request, if it was still waiting for the body to be received from the network.

In 5.5, the definition of request start has been changed to be when the header and body have both been read. This has the effect of more accurately reflecting the time spent by the Data Service in servicing a request, as the time the body spends in transit over the network is no longer included. As a result command timings for affected request will have shorter durations compared to how they were measured before 5.5.


The Couchbase Server 5.5 Windows installer package no longer bundles the DLL dbghelp.dll which is required by Breakpad to produce dumps on Windows platforms. Starting version 5.5, Breakpad will pick the DLL (dbghelp.dll) that is shipped with the OS.

New Supported Platforms

This release adds support for the Debian 9 platform. See Supported Platforms for the complete list of supported platforms.

Deprecated Features and Platforms

The following functionality is deprecated, will be deprecated or is unsupported.

  • Server side Moxi or buckets with custom server side Moxi ports are deprecated and may be removed from the product in the future.

  • The ability to create a bucket with a Moxi port has been deprecated. The CLI commands have been updated to remove Moxi ports for bucket create and bucket edit operations.

Known Issues

Administration/Cluster Management

Issue Description


Summary: Performance issues may be observed when running Couchbase Server on CentOS 7.3 with kernel 3.10.0-514.6.


Summary: On an undersized node, the default memory quota assigned to all the selected services by the server might result in a failure.

Workaround: Adjust the memory allocations appropriately to work around this issue.

Data Service

Issue Description


Summary: Memcached process unable to start if IPv6 protocol stack has been disabled. Workaround: There are two generally accepted methods to disable IPv6 on recent Linux distributions:

  1. Disable the entire IPv6 protocol stack - typically by adding a boot-time grub parameter: ipv6.disable=1.

  2. Disable assignment of IPv6 addresses to interfaces - either by setting the boot-time grub parameter: ipv6.disable_ipv6=1, or dynamically by setting the appropriate net.ipv6.conf sysctl properties.

Only the first method to disable IPv6 will cause Memcached to not start correctly. As a workaround you can disable IPv6 using the second method instead.


Summary: The data node is in a pending state after memcached crashes.


Summary: The last_modified can be incorrect if a bucket was upgraded and contains old documents.


Summary: Couchbase Server can get into a livelock state due to high checkpoint memory usage.

Eventing Service

Issue Description


Summary: The debugger is unable to apply the source map generated by the transpiler. A recent update in the Chrome browser version 66.0.3359.181 is causing this issue. Since Google doesn’t allow previous versions of Chrome to be downloaded, you can download previous versions of Chromium. The debugger works fine with source maps on Chromium version 63.0.3239.0.

Note: Our fix for Chromium is tagged to 69.0.3466.0~157. As per the Chrome release calendar, 69.x is set to release on September 4th 2018. The fix has been merged to Chrome Canary and is available at https://www.google.com/chrome/browser/canary.html


Summary: Multiple mutations are observed for a single document update when using Sync Gateway, leading to the OnUpdate handler being triggered multiple times.


Summary: The eventing service may mark redacted data incorrectly.


Summary: When a rebalance is in progress the Eventing service hangs when memcached is killed on data and eventing nodes.


Summary: The Eventing service currently does not provide the ability to specify a port range. Instead, the OS arbitrarily allocates a port for the Chrome Debugger.


Summary: The eventing service misses some mutations with non-default vBuckets (535,1001 etc).


Summary: The eventing service rebalance progress jumps from 24% to Finish.


Summary: The execution_stats.on_update_failure are not counted in the Failures stats displayed in the Web Console.


Summary: When there are multiple functions being deployed, undeployment does not happen until all functions are deployed.


Summary: Benign panics can be seen in the eventing service logs during undeployment.

Full-text Search Service

Issue Description


Summary: In some circumstances, the Search engine uses more memory than its defined quota.


Summary: The memory usage during index build overshoots the RAM quota.


Summary: Scorch indexes were found to contain duplicate pindexes.


Summary: On Windows platform, a very high memory/CPU usage may be observed when search service is indexing.

Indexing Service

Issue Description


Summary: An error is seen during a SUM aggregate pushdown when the entry value is greater than MaxInt64.


Summary: The rebalance progress in percentage during GSI swap rebalance doesn’t always increase linearly.


Summary: Rebalance fails when taking out failed over nodes running views, in certain circumstances.

Install and Upgrade

Issue Description


Summary: Upgrading from 4.x to 5.x version of Couchbase Server causes an outage for GSI standard indexes. This is observed during rolling upgrade from ForestDB to Plasma. When the last ForestDB index service node is taken out of the cluster, the cluster compatibility mode changes to Plasma and index service restarts.


Summary: In-place (offline) upgrades Server on Windows from 5.0.x or 5.1.x to later releases will fail.

Workaround: Manually uninstall 5.0.x / 5.1.x from your Windows machines prior to installing 5.5.0 or later Server releases.

Query Service

Issue Description

MB-29391, MB-29393

Summary: Large numeric values are reported incorrectly. For example, the modulo operation or a scan for min int64 value returns an incorrect result in case of int64.


Issue Description


Summary: The default "administrator" user doesn’t show up in list of local users displayed on the Web Console under the Security -> Users tab.

Tools, Web Console (UI), and REST API

Issue Description


Summary: The UI displays an incorrect flag in the warning message about the removal of dedicated port for a bucket. It displays --remove-port instead of --remove-bucket-port.

Analytics Service (Developer Preview)

Issue Description


Summary: It is possible for a CONNECT BUCKET statement to fail temporarily with the error message "The vbucket belongs to another server(0x7)" when rebalancing Data nodes.

Workaround: Retry the operation.


Summary: The Analytics stats for failed record count was incorrect.


Summary: The UNION ALL operation does not work for all query types. For example, a query of the form shown below is not parsed correctly.

(SELECT ... FROM ... WHERE ...)
  (SELECT ... FROM ... WHERE ...)

Workaround: Remove the parentheses around the first subquery block.

  (SELECT ...
    FROM ...
    WHERE ...)

Fixed Issues

Data Service

Issue Description


Couchbase Server could get into a livelock state due to high checkpoint memory usage.


There were a number of issues in Couchbase Server which caused rebalance to fail from time to time. These have been fixed.


Rebalance failed with an "Invalid Format specified for DCP_DELETION" error when data or eventing nodes were swapped in and out of a cluster.


The index service went through a race condition in the storage engine which led to a crash. The crash was most likely to happen if the index service was restarted with existing build indexes and they continued to process mutations after the index service restarted.


The full-text search service repeatedly attempted to setup DCP streams to non-existing vBuckets.

Eventing Service

Issue Description


The Eventing service did not retry bucket operation failures that were determined by the appropriate LCB macro to be retriable.


Rebalance of KV/Eventing nodes can hang if the cluster contains Eventing nodes due to stale authentication info with the GoCB SDK.


Rebalance of data or eventing nodes would hang if the cluster contained Eventing nodes.


If the handler code was not idempotent, the destination bucket contained more docs than expected after a rebalance.


On Windows, orphan processes with .rbf extension were found to be running even after uninstalling Couchbase Server.


Under some circumstances, like a function undergoing bootstrap or buckets referenced by the function (source, metadata, destination) get flushed or deleted, the function could not be undeployed.


After restoring from an enterprise backup of eventing functions, eventing service would not process mutations in the destination cluster.


Deployment fails if the size of the handler code is greater than 1MB.


Redeploying a function resulted in the application log being truncated instead of appending to the existing log.


The Eventing service can crash when processing documents in source buckets with size is greater than 1 MB.


Failed rebalance, when retried, could hang.


Rebalance-in of a data(KV) node after recovery from failover may hang if eventing service is processing mutations.

Index Service

Issue Description


Rebalance would hang during index service rebalance.


If the index files were corrupted, the index service would continue to crash and required a failover or a manual deletion of the corrupted index files to recover.

Query Service

Issue Description


The array indexing plan incorrectly included filter covers.


Fixed an issue on Windows platform where a query with more than 1000 characters could be pasted into the cbq shell only the up to 3 times. Subsequent paste operations resulted in a partial query being pasted.


Fixed an issue where the ORDER BY operator proceeded to sort even after being stopped and could lead to crashes.

Tools, Web Console (UI), and REST API

Issue Description


The logic to confirm unsafe stop rebalance operation on the Web Console has been resurrected.


Cbbackup, cbtransfer and cbrecovery can incorrectly timeout and in rare cases cause data corruption.


The cbrecovery command threw an exception when recovering data from a cluster that had failed over nodes.

Analytics Service (Developer Preview)

Issue Description


It was possible for a rebalance of the Analytics nodes to always fail if:

  • a bucket was in the disconnected state, and

  • the Analytics nodes were at different DCP states.

In that case a common DCP state (required for rebalancing) could not be achieved as no new DCP mutations were received by the Analytics nodes.

Release Notes for Older 5.x Versions