[ColtenOuO]

closes: #49099

Summary

get_json_error() only wraps 400-599 responses in the picklable ServerResponseError -- it needs a custom __reduce__ because a plain httpx.HTTPStatusError requires keyword-only request/response arguments that pickle's default reconstruction can't supply (see #47873, fixed for that path by #48517).

A 3xx response -- e.g. a corporate proxy in front of the API server returning a redirect -- falls outside that range, so
httpx.Response.raise_for_status() raises the bare, unpicklable httpx.HTTPStatusError instead. That crashes the scheduler once the exception crosses a multiprocessing boundary: LocalExecutor.result_queue is a multiprocessing.Queue, and unpickling the exception on the scheduler side fails with the exact "missing keyword-only arguments" TypeError #47873 first reported -- just triggered by a redirect instead of a JSON error body.

Reproduced and confirmed with a standalone script -- the same failure mode as #47873's crash log.

Change

Added _raise_for_status_picklable() in task-sdk/src/airflow/sdk/api/client.py, used by both raise_on_4xx_5xx and raise_on_4xx_5xx_with_note: anything raise_for_status() raises outside the 400-599 range now gets wrapped in a ServerResponseError (picklable) before propagating. Errors inside 400-599 that from_response() couldn't extract a JSON detail
from are left exactly as before -- this only closes the gap for status codes get_json_error() never attempted to wrap in the first place.

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Was generative AI tooling used to co-author this PR?

• Yes -- Claude Code (Sonnet 5) for writing test

[potiuk]

Hello @ColtenOuO - thank you for your contributions to Apache Airflow!

The Airflow community has introduced a limit of 5 open pull requests at a time for contributors without write access to the repository. You currently have 19 open pull requests, so - as a one-time step of introducing the limit - we closed the ones where maintainers have not engaged yet:

• [AIP-94] Add airflowctl Tasks List Command #70472 - [AIP-94] Add airflowctl Tasks List Command
• Let HookToolset retry a failed tool call instead of failing the task #71853 - Let HookToolset retry a failed tool call instead of failing the task
• Fix scheduler crash when the API server response is a redirect #71962 - Fix scheduler crash when the API server response is a redirect
• Fix manually triggered runs blocking a scheduled run at the same logical_date #72003 - Fix manually triggered runs blocking a scheduled run at the same logical_date
• Fix mismatched XCom values when a dynamically mapped task has a gap #72007 - Fix mismatched XCom values when a dynamically mapped task has a gap
• Refactor schema version checks to share target-branch and worktree logic #72070 - Refactor schema version checks to share target-branch and worktree logic
• Document custom OTel metrics endpoint path support #72073 - Document custom OTel metrics endpoint path support
• Batch XCom lookups when resolving a mapped task's expand() arguments #72107 - Batch XCom lookups when resolving a mapped task's expand() arguments
• Remove redundant full-Dag TaskInstance query from the execution API task-states endpoint #72270 - Remove redundant full-Dag TaskInstance query from the execution API task-states endpoint
• Fix asset dependency graph dropping outlets for tasks that both consume and produce #72272 - Fix asset dependency graph dropping outlets for tasks that both consume and produce
• Make supervisor split-line stdout test actually cover the split in Task SDK #72585 - Make supervisor split-line stdout test actually cover the split in Task SDK
• Fix GET /assets/{asset_id} returning 500 when asset events share a timestamp #72599 - Fix GET /assets/{asset_id} returning 500 when asset events share a timestamp
• Show detailed API error messages in UI toasters #72831 - Show detailed API error messages in UI toasters

These pull requests stay open because maintainers are already engaged in them - they count towards your limit:

• Fix output type loss in AgentOperator's human-in-the-loop review #70132 - Fix output type loss in AgentOperator's human-in-the-loop review
• Decode base64 for bytes-typed HookToolset parameters #70433 - Decode base64 for bytes-typed HookToolset parameters
• Allow providers to ship testing Dags separately from example Dags #70541 - Allow providers to ship testing Dags separately from example Dags
• Reject unknown update_mask fields instead of silently ignoring them #71003 - Reject unknown update_mask fields instead of silently ignoring them
• Speed up clearing downstream tasks on large Dags #71203 - Speed up clearing downstream tasks on large Dags
• Add deadline alert coverage to Dag endpoint tests #72296 - Add deadline alert coverage to Dag endpoint tests

This is not a judgement of you or of your changes. We never told contributors before that opening many pull requests at once was a problem, so there is nothing to feel bad about - and nothing is lost: your branches, commits and the review history stay where they are.

What we ask you to do is to make your first prioritization decision: choose which of the pull requests above matter most to you, and reopen them (up to 5 open at a time, including the ones still open) with the "Reopen pull request" button or gh pr reopen <PR_NUMBER> --repo apache/airflow. Reopen the ones you are ready to follow through - keep them rebased, respond to review comments and fix failing checks.

While your pull requests are waiting for review, the most valuable thing you can do is help in other ways - reviewing other contributors' pull requests, helping with issues, and taking part in the discussions on the devlist and Slack.

Why we introduced the limit, what it means for you and how to reopen or restore a pull request is explained in https://github.com/apache/airflow/blob/main/contributing-docs/32_open_pull_request_limit.rst.

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Drafted-by: Claude Code (Opus 5); reviewed by @potiuk before posting