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Fixed occasional bind failures with IPv6 and ephemeral ports #1313

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Merged
agronholm merged 2 commits into from
Sep 6, 2026
+5 −1
Merged

Fixed occasional bind failures with IPv6 and ephemeral ports #1313

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bb339a0
Fixed occasional bind failures with IPv6 and ephemeral ports
agronholm Sep 5, 2026
1132ab0
Merge branch 'master' into bind-fail
agronholm Sep 6, 2026
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4 changes: 4 additions & 0 deletions docs/versionhistory.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,10 @@ This library adheres to `Semantic Versioning 2.0 <http://semver.org/>`_.
across backends (asyncio returned immediately; Trio raised ``ValueError``) by
raising ``ValueError`` on all backends
(`#1306 <https://github.com/agronholm/anyio/issues/1306>`_; PR by @BetterAndBetterII)
- Fixed ``create_tcp_listener()`` occasionally failing with a message like
``Could not create 2 listeners with a consistent port`` when an ephemeral port is
requested and IPv6 is enabled and the dual-stack path is not available or a specific
local host name was given

**4.15.1**

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2 changes: 1 addition & 1 deletion src/anyio/_core/_sockets.py
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Expand Up @@ -393,7 +393,7 @@ def setup_raw_socket(

errors: list[OSError] = []
try:
for _ in range(len(sockaddrs)):
for _ in range(10): # enough to absorb ephemeral port collisions
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listeners: list[SocketListener] = []
bound_ephemeral_port = local_port
try:
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