Release Notes
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Release 3.3 | Release 3.2 | Release 3.1 | Release 3.0 | Archived documentation
Couchbase Sync Gateway
This content describes the key features and changes implemented by release 4.0 of Couchbase Sync Gateway
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One Way Upgrade
The migration to a 4.x configuration is a ONE WAY process — see: Upgrading for more. |
4.0.9 — November 2026
Fixed Issues
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CBG-5851 — ISGR pull stops making progress when the sync function rejects a revision
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CBG-5855 — ISGR pull stops making progress when a deleted revision fails body validation
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CBG-5873 — Checking _index_init status while indexes are being built can crash Sync Gateway
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CBG-5916 — Changes can be missed during cache backfill when server compression is on
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CBG-5938 — Document writes can hang forever when a database closes
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CBG-5954 — ISGR can reconnect endlessly after one failed connection attempt
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CBG-5972 — ISGR replications stop right away after a
PUT /{db}/_config/audit -
CBG-5985 — A disabled user can still use an existing session to read and write documents
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CBG-6019 — CBL pull replication can hang when the client has a document from more than one URL
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CBG-6042 — Shell command injection through sgcollect_info options
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CBG-6079 — Goroutines can leak when a replication connection closes while busy
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CBG-6082 — Sync Gateway shutdown does not stop in-progress database initialization
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CBG-6097 — A race in DCP checkpoint handling can crash Sync Gateway
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CBG-6103 — ISGR cannot push RTE revision to a peer with no revision for the document
4.0.8 — September 2026
Fixed Issues
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CBG-5416 — /db/_index_init can return an error status when stopped Private
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CBG-5741 — Channel cache compact_low_watermark_pct config not wired up correctly
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CBG-5768 — ISGR RunAs does not ensure the given username exists at replication creation or run time
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CBG-5772 — ISGR replications from 4.x <→ 4.x will not update channel, access information
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CBG-5815 — slow channel cache data leak with skipped sequences and active replications
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CBG-5819 — Role deletion with purge=true allocates a sequence and never releases it
4.0.7 — July 2026
| If you use Sync Gateway 4.0.5 or 4.0.6, upgrade to this release to receive critical fixes. |
Fixed Issues
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CBG-5368 — Problem with channel removal macro expansion when channel names have
.in them -
CBG-5383 — Resync regenerate sequences will not set _default metadata id when finished
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CBG-5453 — Subdoc operation failure on multiple channel removal
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CBG-5553 — activeOnly replication can miss documents for channels over the pagination limit
4.0.6 — June 2026
| This version has a known issue, CBG-5554 — activeOnly replication can miss documents for channels over the pagination limit. Please upgrade to Sync Gateway 4.1.1 or later 4.0.7 or later to receive critical fixes. |
4.0.5 — June 2026
| This version has a known issue, CBG-5554 — activeOnly replication can miss documents for channels over the pagination limit. Please upgrade to Sync Gateway 4.1.1 or later 4.0.7 or later to receive critical fixes. |
Fixed Issues
4.0.3 — February 2026
Fixed Issues
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CBG-4949 — Duplicate conflict logging during legacy rev processing
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CBG-4998 — Import feed panics for docs with CV in _sync.rev.ver but no
_vv xattr -
CBG-5016 — Panic in _config?include_runtime=true endpoint when database has failed to start
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CBG-5042 — Couchbase Server timeout error causes panic in GetUser
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CBG-5055 — Non-integer sequence numbers are incorrectly encoded for
norevmessages for CBL -
CBG-5107 — Channel information unavailable for non-current revisions
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CBG-5132 — Clients fetching a delta can panic when the revision cache is disabled
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CBG-5135 — Current revision attachments can be loaded when loading backup rev by CV
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CBG-5146 — replacement revs never utilized for unfiltered replications
4.0.2 — December 2025
4.0.0 — October 2025
Enhancements
Upgrading
For more on upgrading — see: Upgrading