---
name: Python SDK
slug: launchdarkly-python-sdk
type: github
source_url: https://github.com/launchdarkly/python-server-sdk
changelog_url: https://github.com/launchdarkly/python-server-sdk/blob/HEAD/CHANGELOG.md
organization: LaunchDarkly
organization_slug: launchdarkly
total_releases: 122
latest_version: 9.15.1
latest_date: 2026-04-14
last_updated: 2026-04-18
tracking_since: 2015-10-07
canonical: https://releases.sh/launchdarkly/launchdarkly-python-sdk
organization_url: https://releases.sh/launchdarkly
---

<Summary type="rolling" window-days="90" release-count="1">
The Python SDK tightened its platform support and API contracts. Python 3.9 dropped out of the supported matrix, while ChangeSet now requires a Selector argument—a breaking change that strengthens the data model. A race condition in FeatureStore's update_availability path got fixed alongside safer lock handling via context managers.
</Summary>

<Release version="9.15.1" date="April 14, 2026" published="2026-04-14T16:19:40.000Z" url="https://github.com/launchdarkly/python-server-sdk/releases/tag/9.15.1">
## v9.15.1

## [9.15.1](https://github.com/launchdarkly/python-server-sdk/compare/9.15.0...9.15.1) (2026-04-10)


### Bug Fixes

* Improve fallback behavior when using custom data system configuration ([#407](https://github.com/launchdarkly/python-server-sdk/issues/407)) ([60272b2](https://github.com/launchdarkly/python-server-sdk/commit/60272b2881847de04a5b771e6d28f3deefc1222d))

---
This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please).

<!-- CURSOR_SUMMARY -->
</Release>

<Release version="9.15.0" date="February 10, 2026" published="2026-02-10T17:35:16.000Z" url="https://github.com/launchdarkly/python-server-sdk/releases/tag/9.15.0">
## v9.15.0

## [9.15.0](https://github.com/launchdarkly/python-server-sdk/compare/9.14.1...9.15.0) (2026-02-10)


### Features

* Drop support for python 3.9 ([#393](https://github.com/launchdarkly/python-server-sdk/issues/393)) ([5b761bd](https://github.com/launchdarkly/python-server-sdk/commit/5b761bd306e1e6973b59cea3f7657463de0204d1))
* Update ChangeSet to always require a Selector ([#405](https://github.com/launchdarkly/python-server-sdk/issues/405)) ([5dc4f81](https://github.com/launchdarkly/python-server-sdk/commit/5dc4f81688e814045373edb244e0420fa572d922))


### Bug Fixes

* Add context manager for clearer, safer locks ([#396](https://github.com/launchdarkly/python-server-sdk/issues/396)) ([beca0fa](https://github.com/launchdarkly/python-server-sdk/commit/beca0fa4985f385cb3328408528e14696ec7c70f))
* Address potential race condition in FeatureStore update_availability ([#391](https://github.com/launchdarkly/python-server-sdk/issues/391)) ([31cf487](https://github.com/launchdarkly/python-server-sdk/commit/31cf4875c35f08177105a16f65140acabe93d3da))
* Allow modifying fdv2 data source options independent of main config ([#403](https://github.com/launchdarkly/python-server-sdk/issues/403)) ([d78079e](https://github.com/launchdarkly/python-server-sdk/commit/d78079e7f340690c17f39ef73dd9a45e6f365fd7))
* Mark copy_with_new_sdk_key method as deprecated ([#353](https://github.com/launchdarkly/python-server-sdk/issues/353)) ([e471ccc](https://github.com/launchdarkly/python-server-sdk/commit/e471ccc3d5f4c37452d8a2ebba58248ca0a155dd))
* Prevent immediate polling on recoverable error ([#399](https://github.com/launchdarkly/python-server-sdk/issues/399)) ([da565a2](https://github.com/launchdarkly/python-server-sdk/commit/da565a2dce67fc386396686dd2017819e2c4edfb))
* Redis store is considered initialized when `$inited` key is written ([e99a27d](https://github.com/launchdarkly/python-server-sdk/commit/e99a27d48f1fc2bd81b1791fd57cb1a8ab754569))
* Stop FeatureStoreClientWrapper poller on close ([#397](https://github.com/launchdarkly/python-server-sdk/issues/397)) ([468afdf](https://github.com/launchdarkly/python-server-sdk/commit/468afdfef32f74f7cc82cb61f01f5674054da9db))
* Update DataSystemConfig to accept list of synchronizers ([#404](https://github.com/launchdarkly/python-server-sdk/issues/404)) ([c73ad14](https://github.com/launchdarkly/python-server-sdk/commit/c73ad14090ef1378af1bfbe626a74eb369e3cac8))
* Update reason documentation with inExperiment value ([#401](https://github.com/launchdarkly/python-server-sdk/issues/401)) ([cbfc3dd](https://github.com/launchdarkly/python-server-sdk/commit/cbfc3dd8876eae9ffa352ec12a1131a64110c08a))
* Update Redis to write missing `$inited` key ([e99a27d](https://github.com/launchdarkly/python-server-sdk/commit/e99a27d48f1fc2bd81b1791fd57cb1a8ab754569))

---
This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please).

<!-- CURSOR_SUMMARY -->
</Release>

<Release version="9.14.1" date="December 15, 2025" published="2025-12-15T18:00:33.000Z" url="https://github.com/launchdarkly/python-server-sdk/releases/tag/9.14.1">
## v9.14.1

## [9.14.1](https://github.com/launchdarkly/python-server-sdk/compare/9.14.0...9.14.1) (2025-12-15)


### Bug Fixes

* Remove all synchronizers in daemon mode ([#388](https://github.com/launchdarkly/python-server-sdk/issues/388)) ([441a5ec](https://github.com/launchdarkly/python-server-sdk/commit/441a5ecb3d3f1428801c44b875b32ef396df2fa3))

---
This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please).

<!-- CURSOR_SUMMARY -->
</Release>

<Release version="9.14.0" date="December 4, 2025" published="2025-12-04T16:57:23.000Z" url="https://github.com/launchdarkly/python-server-sdk/releases/tag/9.14.0">
## v9.14.0

## [9.14.0](https://github.com/launchdarkly/python-server-sdk/compare/9.13.1...9.14.0) (2025-12-04)


### Features

* adding data system option to create file datasource intializer ([e5b121f](https://github.com/launchdarkly/python-server-sdk/commit/e5b121f92a09fcaf717f88b426348798961ab62e))
* adding file data source as an intializer ([#381](https://github.com/launchdarkly/python-server-sdk/issues/381)) ([3700d1d](https://github.com/launchdarkly/python-server-sdk/commit/3700d1ddd9ef6c7a505ec24783c71753cea89abb))


### Bug Fixes

* Add warning if relying on Redis `max_connections` parameter ([#387](https://github.com/launchdarkly/python-server-sdk/issues/387)) ([e6395fa](https://github.com/launchdarkly/python-server-sdk/commit/e6395fa5316bef1c0d2829b4cc4b655fece8b8ea)), closes [#386](https://github.com/launchdarkly/python-server-sdk/issues/386)
* modified initializer behavior to spec ([064f65c](https://github.com/launchdarkly/python-server-sdk/commit/064f65c76135c385a6fdcb0209caa0e7a8cf872c))

---
This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please).

<!-- CURSOR_SUMMARY -->
</Release>

<Release version="9.13.1" date="November 19, 2025" published="2025-11-19T23:38:06.000Z" url="https://github.com/launchdarkly/python-server-sdk/releases/tag/9.13.1">
## v9.13.1

## [9.13.1](https://github.com/launchdarkly/python-server-sdk/compare/9.13.0...9.13.1) (2025-11-19)


### Bug Fixes

* Include ldclient.datasystem in docs ([#379](https://github.com/launchdarkly/python-server-sdk/issues/379)) ([318c6fe](https://github.com/launchdarkly/python-server-sdk/commit/318c6fea0738d296713768afc8e08ee9b2360dc2))

---
This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please).

<!-- CURSOR_SUMMARY -->
</Release>

<Release version="9.13.0" date="November 19, 2025" published="2025-11-19T22:21:52.000Z" url="https://github.com/launchdarkly/python-server-sdk/releases/tag/9.13.0">
## v9.13.0

## [9.13.0](https://github.com/launchdarkly/python-server-sdk/compare/9.12.3...9.13.0) (2025-11-19)


### Features

* **experimental:** Release EAP support for FDv2 data system ([#376](https://github.com/launchdarkly/python-server-sdk/issues/376)) ([0e7c32b](https://github.com/launchdarkly/python-server-sdk/commit/0e7c32b4df12daef25e9b2e9b637225c3e74a2dd))

---
This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please).

<!-- CURSOR_SUMMARY -->
</Release>

<Release version="9.12.3" date="October 30, 2025" published="2025-10-30T18:56:59.000Z" url="https://github.com/launchdarkly/python-server-sdk/releases/tag/9.12.3">
## v9.12.3

## [9.12.3](https://github.com/launchdarkly/python-server-sdk/compare/9.12.2...9.12.3) (2025-10-30)


### Bug Fixes

* Fix overly generic type hint on File data source ([#365](https://github.com/launchdarkly/python-server-sdk/issues/365)) ([52a7499](https://github.com/launchdarkly/python-server-sdk/commit/52a7499f7cf1d4311f89fa98e65bca670e127aa6)), closes [#364](https://github.com/launchdarkly/python-server-sdk/issues/364)

---
This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please).

<!-- CURSOR_SUMMARY -->
</Release>

<Release version="9.12.2" date="October 27, 2025" published="2025-10-27T20:13:06.000Z" url="https://github.com/launchdarkly/python-server-sdk/releases/tag/9.12.2">
## v9.12.2

## [9.12.2](https://github.com/launchdarkly/python-server-sdk/compare/9.12.1...9.12.2) (2025-10-27)


### Bug Fixes

* Fix incorrect event count in failure message ([#359](https://github.com/launchdarkly/python-server-sdk/issues/359)) ([91f4163](https://github.com/launchdarkly/python-server-sdk/commit/91f416329bd3e53a622ce58caa63cdd6cdcc8896))

---
This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please).

<!-- CURSOR_SUMMARY -->
</Release>

<Release version="9.12.1" date="September 30, 2025" published="2025-09-30T18:03:00.000Z" url="https://github.com/launchdarkly/python-server-sdk/releases/tag/9.12.1">
## v9.12.1

## [9.12.1](https://github.com/launchdarkly/python-server-sdk/compare/9.12.0...9.12.1) (2025-09-30)


### Bug Fixes

* Add validation format check for SDK key ([#351](https://github.com/launchdarkly/python-server-sdk/issues/351))

---
This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please).

<!-- CURSOR_SUMMARY -->
</Release>

<Release version="9.12.0" date="July 14, 2025" published="2025-07-14T16:03:46.000Z" url="https://github.com/launchdarkly/python-server-sdk/releases/tag/9.12.0">
## v9.12.0

## [9.12.0](https://github.com/launchdarkly/python-server-sdk/compare/9.11.1...9.12.0) (2025-07-11)


### ⚠ BREAKING CHANGES

* Drop support for Python 3.8 (eol 2024-10-07) ([#339](https://github.com/launchdarkly/python-server-sdk/issues/339))

### Features

* Add support for plugins. ([#337](https://github.com/launchdarkly/python-server-sdk/issues/337)) ([241f6f4](https://github.com/launchdarkly/python-server-sdk/commit/241f6f49b203044f801fdfc976f7d446225ec5e1))
* Drop support for Python 3.8 (eol 2024-10-07) ([#339](https://github.com/launchdarkly/python-server-sdk/issues/339)) ([0207665](https://github.com/launchdarkly/python-server-sdk/commit/02076650064d8a20f792c80cda3249a7aa7e336a))
</Release>

<Release version="9.11.1" date="May 29, 2025" published="2025-05-29T19:33:32.000Z" url="https://github.com/launchdarkly/python-server-sdk/releases/tag/9.11.1">
## v9.11.1

## [9.11.1](https://github.com/launchdarkly/python-server-sdk/compare/9.11.0...9.11.1) (2025-05-29)


### Bug Fixes

* Raise minimum eventsource dep to v1.2.4 ([#333](https://github.com/launchdarkly/python-server-sdk/issues/333)) ([5270962](https://github.com/launchdarkly/python-server-sdk/commit/527096275c20668041436b770270375be397033b))
</Release>

<Release version="9.11.0" date="April 16, 2025" published="2025-04-16T18:25:35.000Z" url="https://github.com/launchdarkly/python-server-sdk/releases/tag/9.11.0">
## v9.11.0

## [9.11.0](https://github.com/launchdarkly/python-server-sdk/compare/9.10.0...9.11.0) (2025-04-08)


### Features

* Add `postfork` method to re-initialize after forking ([#329](https://github.com/launchdarkly/python-server-sdk/issues/329)) ([581fcfb](https://github.com/launchdarkly/python-server-sdk/commit/581fcfb5d7df36219f5735e21097838c323c13da))
</Release>

<Release version="9.10.0" date="March 13, 2025" published="2025-03-13T20:40:43.000Z" url="https://github.com/launchdarkly/python-server-sdk/releases/tag/9.10.0">
## v9.10.0

## [9.10.0](https://github.com/launchdarkly/python-server-sdk/compare/9.9.0...9.10.0) (2025-03-13)


### Features

* Inline context for custom and migration op events ([#327](https://github.com/launchdarkly/python-server-sdk/issues/327)) ([ecfd56c](https://github.com/launchdarkly/python-server-sdk/commit/ecfd56cc916c72095764349741a0396d295f932f))
</Release>

<Release version="9.9.0" date="January 3, 2025" published="2025-01-03T15:14:57.000Z" url="https://github.com/launchdarkly/python-server-sdk/releases/tag/9.9.0">
## v9.9.0

## [9.9.0](https://github.com/launchdarkly/python-server-sdk/compare/9.8.1...9.9.0) (2025-01-03)


### Features

* Add support for payload filtering ([#323](https://github.com/launchdarkly/python-server-sdk/issues/323)) ([1115afb](https://github.com/launchdarkly/python-server-sdk/commit/1115afb454ac6ca16e1ff44cc73aa4d683786188))
</Release>

<Release version="9.8.1" date="December 23, 2024" published="2024-12-23T16:35:10.000Z" url="https://github.com/launchdarkly/python-server-sdk/releases/tag/9.8.1">
## v9.8.1

## [9.8.1](https://github.com/launchdarkly/python-server-sdk/compare/9.8.0...9.8.1) (2024-12-23)


### Bug Fixes

* Close SSE thread on shutdown ([#320](https://github.com/launchdarkly/python-server-sdk/issues/320)) ([2210658](https://github.com/launchdarkly/python-server-sdk/commit/22106589cb1886db6fc878e5701fdb7bc7e2537a))
</Release>

<Release version="9.8.0" date="October 16, 2024" published="2024-10-16T17:17:17.000Z" url="https://github.com/launchdarkly/python-server-sdk/releases/tag/9.8.0">
## v9.8.0

## [9.8.0](https://github.com/launchdarkly/python-server-sdk/compare/9.7.2...9.8.0) (2024-10-16)


### Features

* Add support for client-side prerequisite events ([#314](https://github.com/launchdarkly/python-server-sdk/issues/314)) ([3025af4](https://github.com/launchdarkly/python-server-sdk/commit/3025af4dc6499c678e30bb2ae240a30b8c89f101))
</Release>

<Release version="9.7.2" date="October 1, 2024" published="2024-10-01T18:09:06.000Z" url="https://github.com/launchdarkly/python-server-sdk/releases/tag/9.7.2">
## v9.7.2

## [9.7.2](https://github.com/launchdarkly/python-server-sdk/compare/9.7.1...9.7.2) (2024-10-01)


### Bug Fixes

* Set explicit names for each spawned thread ([#311](https://github.com/launchdarkly/python-server-sdk/issues/311)) ([9c7777c](https://github.com/launchdarkly/python-server-sdk/commit/9c7777ca4d628f1d19de631310bf8ae5d90ab60a))
* Shutdown diagnostic thread if enabled ([#312](https://github.com/launchdarkly/python-server-sdk/issues/312)) ([cde6cfb](https://github.com/launchdarkly/python-server-sdk/commit/cde6cfbbaab81d5c20ba0e83cac030f1a4a333ad))
</Release>

<Release version="9.7.1" date="August 26, 2024" published="2024-08-26T18:46:26.000Z" url="https://github.com/launchdarkly/python-server-sdk/releases/tag/9.7.1">
## v9.7.1

## [9.7.1](https://github.com/launchdarkly/python-server-sdk/compare/9.7.0...9.7.1) (2024-08-26)


### Bug Fixes

* Skip empty hosts when processing NO_PROXY variable ([#309](https://github.com/launchdarkly/python-server-sdk/issues/309)) ([82d8117](https://github.com/launchdarkly/python-server-sdk/commit/82d8117bcc375ffd8c3028589905dd4005e31b5a))
</Release>

<Release version="9.7.0" date="August 21, 2024" published="2024-08-21T13:48:57.000Z" url="https://github.com/launchdarkly/python-server-sdk/releases/tag/9.7.0">
## v9.7.0

## [9.7.0](https://github.com/launchdarkly/python-server-sdk/compare/9.6.0...9.7.0) (2024-08-20)


### Features

* Add option to omit anonymous users from index and identify events ([#306](https://github.com/launchdarkly/python-server-sdk/issues/306)) ([8f13ffe](https://github.com/launchdarkly/python-server-sdk/commit/8f13ffe965b13df6398746866d464722d70e8508))
</Release>

<Release version="9.6.0" date="August 19, 2024" published="2024-08-19T14:43:53.000Z" url="https://github.com/launchdarkly/python-server-sdk/releases/tag/9.6.0">
## v9.6.0

## [9.6.0](https://github.com/launchdarkly/python-server-sdk/compare/9.5.0...9.6.0) (2024-08-19)


### Features

* `NO_PROXY` environment variable can be used to override `HTTP(S)_PROXY` values ([#301](https://github.com/launchdarkly/python-server-sdk/issues/301)) ([d0913ee](https://github.com/launchdarkly/python-server-sdk/commit/d0913ee44b5fffce70dfd3b01631cc0817f1b2e8))
</Release>

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