3.7 - Prefect

3.7.3 - Scheduler go brrrr

Released on June 01, 2026 Automatic dependency installation for pulled-code deployments is now opt-in. In 3.7.2, the runner would automatically prepare project dependencies when a deployment pulled code containing a pyproject.toml. This behavior is now disabled by default. Set PREFECT_RUNNER_AUTO_INSTALL_DEPENDENCIES=true (or runner.auto_install_dependencies = true in your profile) to re-enable it. Enhancements ➕➕

Expose WebSocket ping interval/timeout settings for uvicorn by @chuqCTC in #22091
Activate scheduler partial index for faster scheduling queries by @zzstoatzz in #22111
Lazify prefect.server package exports for faster imports by @devin-ai-integration[bot] in #22122

Bug Fixes 🐞

Raise pydantic-settings lower bound to >=2.9.1 by @devin-ai-integration[bot] in #22075
Cap reconnect_delay exponent to prevent OverflowError by @devin-ai-integration[bot] in #22086
Guard ZeroDivisionError in RetryFailedTasks when retry_jitter_factor is set without retry_delay by @devteamaegis in #22071
Redact API URL userinfo in client errors by @devin-ai-integration[bot] in #22098
Execute local deployment paths in place by @devin-ai-integration[bot] in #22100
Preserve persisted result metadata by @desertaxle in #22110
Make runner dependency installation opt-in by @desertaxle in #22116
Preserve TaskRunRecorder upsert order by @desertaxle in #22112
Lowercase work pool name in block document names for storage configure by @devin-ai-integration[bot] in #22144
Remove double client injection in _resolve_flow_for_hooks by @devin-ai-integration[bot] in #22176

Integrations & Dependencies 🤝

Bump starlette to 1.2.0 for CVE-2026-48710 by @zzstoatzz in #22145

Development & Tidiness 🧹

Add server-side cleanup queue storage for worker communication by @desertaxle in #22041
Don’t copy file-derived labels from linked issues by @zzstoatzz in #22115
Support string keys in temporary_settings by @zzstoatzz in #22120
Clean up WebSocket ping settings surface and tests by @devin-ai-integration[bot] in #22117
Fix flaky tests on main — regenerate SettingAccessor and widen timing tolerance by @devin-ai-integration[bot] in #22133
Add timeout and transport retries to hosted_api_client fixture by @devin-ai-integration[bot] in #22130
Use direct API calls in suspension integration test by @devin-ai-integration[bot] in #22157
Use direct API calls in suspension integration test by @devin-ai-integration[bot] in #22152
Pin local worker registry in test_create_with_unsupported_type by @devin-ai-integration[bot] in #22153
Remove unneeded clear_db markers from isolated test modules by @devin-ai-integration[bot] in #22102
Update CODEOWNERS to remove obsolete entries by @desertaxle in #22178

Documentation 📓

Fix work-pool concurrency command examples by @devin-ai-integration[bot] in #22093
Clarify non-interactive Prefect Cloud login requirements by @devin-ai-integration[bot] in #22095
Fix multi-worker server docs Redis requirements by @devin-ai-integration[bot] in #22107

Full Changelog: https://github.com/PrefectHQ/prefect/compare/3.7.2…3.7.3

3.7.2 - Delete after running

Released on May 22, 2026 Enhancements ➕➕

Add delete flow run automation action by @zzstoatzz in #22018
Add worker channel handshake and heartbeat by @desertaxle in #22004
Add work-pool snapshot delivery to worker channel by @desertaxle in #22026
Index triggers by expect pattern to avoid O(n) scan in find_interested_triggers by @chuqCTC in #21977
Cache variable reads within a single resolve_variables() call by @devin-ai-integration[bot] in #22060
Cache block document template resolution by @zzstoatzz in #22065
Validate PEP 508 dependencies in execute_bundle_in_subprocess by @theluckystrike in #21916

Bug Fixes 🐞

Remove redundant submitted_ids set in ScheduledRunPoller by @J3r3myPerera in #21982
Fix Apprise logger level normalization by @hemantmm in #21709
Handle concurrent work-pool creation in worker REST fallback by @1fanwang in #21919
Use stdlib importlib.metadata instead of importlib_metadata backport by @devin-ai-integration[bot] in #22012
Improve missing block reference error messages by @hemantmm in #21945
Correctly check process liveness before adding to process map by @J3r3myPerera in #22006
Fix Azure blob result storage to overwrite on rewrite by @wtfashwin in #22035
Surface actionable error when UI static files fail due to insufficient disk space by @devin-ai-integration[bot] in #22057
Route lease renewal failure log through run logger by @zzstoatzz in #22053
Show clean CLI error for malformed TOML settings files by @devin-ai-integration[bot] in #22030
Make ZipBuilder storage keys truly content-addressed by @devin-ai-integration[bot] in #22008
Fix default result store existence checks by @desertaxle in #22058
Fix worker-channel ready frame returning worker_id=None by @devin-ai-integration[bot] in #22067

Development & Tidiness 🧹

Make test_flow_parameter_caching deterministic by @devin-ai-integration[bot] in #21973
Widen suspension propagation window in external-suspension integration test by @devin-ai-integration[bot] in #21972
Fix flaky test_worker integration test with event subscription race by @devin-ai-integration[bot] in #22010
Make test_read_flow_runs_filters_by_start_time deterministic by @devin-ai-integration[bot] in #22024
Speed up client test CI shards by @desertaxle in #22003
Add import-performance guardrails by @devin-ai-integration[bot] in #22002
Flip clear_db marker from opt-out to opt-in by @desertaxle in #21918
Measure true cold imports in CodSpeed benchmarks by @devin-ai-integration[bot] in #22019
Fix low-risk import cycles by @devin-ai-integration[bot] in #22040

Documentation 📓

Replace stale prefect run CLI example with python by @devin-ai-integration[bot] in #22013
Fix stale internal links on work-pools concept page by @devin-ai-integration[bot] in #22031
Fix retired deployment-doc links in create-deployments page by @devin-ai-integration[bot] in #22061
Update Airflow migration guide to use prefect deploy + prefect.yaml by @devin-ai-integration[bot] in #22059
Add delete-flow-run automation action to action types table by @github-actions[bot] in #22021

Full Changelog: https://github.com/PrefectHQ/prefect/compare/3.7.1…3.7.2

3.7.1 - Don’t touch that dial!

Released on May 16, 2026 Enhancements ➕➕

Add deployment_name logging variable by @devin-ai-integration[bot] in #21804
Infer logs page size from API response in CLI by @alighazi288 in #21711
Add default result storage CLI by @zzstoatzz in #21771
Add Pydantic-aware tojson template filter by @devin-ai-integration[bot] in #21861
Add worker channel protocol contract by @desertaxle in #21859
Add worker channel client with REST fallback by @desertaxle in #21885
Add worker cleanup executor by @desertaxle in #21895
Add worker work-pool snapshot handling by @desertaxle in #21898
Add cancelling_timeout_teardown.v1 cleanup handler by @desertaxle in #21911

Bug Fixes 🐞

Fix flow run logs download from Prefect UI in browser by @baltic-tea in #21718
Fix flow run suspension at orchestration boundaries by @desertaxle in #21875
Clear default result storage when deleting block by @zzstoatzz in #21862
Preserve trailing slash when redirecting to V2 UI by @zzstoatzz in #21912
Fix concurrency lease renewal starvation with thread-backed renewal by @desertaxle in #21925
Enforce tz-aware DateTime on Python >= 3.13 by @zzstoatzz in #21952
Fix subflow duplication when process is re-executed against same flow_run_id by @devin-ai-integration[bot] in #21951
Reject COMPLETED→COMPLETED transitions that discard result data by @saschwartz in #21956
Use tz-aware now("UTC") for last_adhoc_pull timestamp in runner by @J3r3myPerera in #21961
Guard .get() calls on arbitrary State.data in result-data-loss rules by @devin-ai-integration[bot] in #21967

Integrations & Dependencies 🤝

Bump prefect-github extra floor to >=0.4.2 by @zzstoatzz in #21946

Development & Tidiness 🧹

Fix flaky test_flow_run_execute_cancellation_runs_nested_subflow_hooks by @devin-ai-integration[bot] in #21866
Migrate low-risk private modules to _internal (batch 1 of 3) by @devin-ai-integration[bot] in #21879
Migrate medium-complexity private modules to _internal (batch 2) by @devin-ai-integration[bot] in #21881
Migrate _result_records.py and utilities/_engine.py to _internal/ (batch 3) by @devin-ai-integration[bot] in #21880
Label agents-md-update PRs and exclude from changelog by @devin-ai-integration[bot] in #21910
Fix duplicated “the” in flow_run_slas test comments by @lphuc2250gma in #21943
Widen timing tolerance in test_renew_concurrency_lease by @devin-ai-integration[bot] in #21965
Fix flaky test_reschedule_flow_runs timeout under CI load by @devin-ai-integration[bot] in #21966
Harden AGENTS.md auto-sync reviews by @devin-ai-integration[bot] in #21975

Documentation 📓

Document default result storage by @zzstoatzz in #21774
Document published REST OpenAPI schema by @zzstoatzz in #21844
Mark server-side default result storage as beta by @zzstoatzz in #21877
Document context propagation for threads in add-logging guide by @jbbqqf in #21883
Recommend managed automation for zombie detection by @bunchesofdonald in #21894
Add unlisted infrastructure debugging overview page by @devin-ai-integration[bot] in #21900
Note metric-trigger Cloud gating and event prefix difference by @zzstoatzz in #21935

Full Changelog: https://github.com/PrefectHQ/prefect/compare/3.7.0…3.7.1

3.7.0 - Our little features are all grown up 🥲

Released on May 06, 2026 New Features 🎉

Graduate infrastructure decorators to GA by @desertaxle in #21784
Promote plugin system from experimental to GA by @desertaxle in #21787
Add isolated workspace resolver for flow run setup by @desertaxle in #21699

Enhancements ➕➕

Support inline block placeholder substitution by @hemantmm in #21777
Render Mermaid.js diagrams in Markdown blocks in ui-v2 by @devin-ai-integration[bot] in #21793
Eliminate O(N²) checksum scan in read_block_schemas by @VittoriaLanzo in #21754
Add per-browser UI version switcher by @desertaxle in #21706
Add server default result storage config surface by @zzstoatzz in #21532
Route server default result storage through runtime resolution by @zzstoatzz in #21759
Add flow.generate_mermaid_graph() method for dependency-free flow visualization by @znicholasbrown in #21786
Route flow-run execute through workspace resolver by @desertaxle in #21796
Add flow engine module entrypoint by @desertaxle in #21799
Run prepared pyproject workspaces with uv by @desertaxle in #21801
Warn when nested ThreadPoolTaskRunner submission would deadlock by @devin-ai-integration[bot] in #21800
Add cycle detection for block_document references by @Lougarou in #21829

Bug Fixes 🐞

Use now() helper instead of DateTime.now() in deployment CLI by @devin-ai-integration[bot] in #21769
Fix race condition in GitRepository.pull_code() with file-based locking by @devin-ai-integration[bot] in #21388
Retry record_bulk_task_run_events on IntegrityError by @devin-ai-integration[bot] in #21813
Set custom flow run names before Running events by @devin-ai-integration[bot] in #21803
Prevent deadlock in mark_deployments_ready / mark_deployments_not_ready by @chuqCTC in #21792
Fix V2 concurrency lease release errors by @devin-ai-integration[bot] in #21797

Development & Tidiness 🧹

Avoid run_coro_as_sync deadlock in wait futures test by @devin-ai-integration[bot] in #21766
Widen timing tolerance for test_flow_run_lateness_when_scheduled by @devin-ai-integration[bot] in #21781
Widen flow timeout in test_timeout_concurrency_slot_released by @devin-ai-integration[bot] in #21788
Add apt retry config to old-sqlite.Dockerfile by @devin-ai-integration[bot] in #21814
Use thread-based pytest-timeout for test_timeout_stops_execution_at_next_task_for_sync_flows by @devin-ai-integration[bot] in #21819
Add zombie flow detection trigger regression test by @devin-ai-integration[bot] in #21802

Full Changelog: https://github.com/PrefectHQ/prefect/compare/3.6.29…3.7.0

Documentation Index

​3.7.3 - Scheduler go brrrr

​3.7.2 - Delete after running

​3.7.1 - Don’t touch that dial!

​3.7.0 - Our little features are all grown up 🥲

3.7.3 - Scheduler go brrrr

3.7.2 - Delete after running

3.7.1 - Don’t touch that dial!

3.7.0 - Our little features are all grown up 🥲