opentelemetry-api breaking changes

1.45.1

4 breaking changes, first published October 6, 2026.

• Behavior changed
  The API now discards tracestate headers longer than 8192 characters instead of parsing them. Code that depends on very long tracestate values will see them dropped. github.com
• Default changed
  The OTLP proto HTTP exporter again uses requests as its default HTTP transport, so proxy environment variables such as HTTPS_PROXY are honored. Users who relied on the 1.45.0 transport should check their proxy and transport setup. github.com
• Signature changed opentelemetry.util.types.AnyValue
  Was AnyValue; now AnyValue: TypeAlias. pypi.org
• Signature changed opentelemetry.util.types.AttributeValue
  Was AttributeValue; now AttributeValue: TypeAlias. pypi.org

1.45.0

21 breaking changes, first published September 25, 2026.

• Behavior changed opentelemetry.api.trace.span.TraceState
  Subclasses of Logger must now implement the enabled method, or they will break. github.com
• Behavior changed opentelemetry.exporter.otlp.proto.http
  The default HTTP backend for the OTLP proto HTTP exporter changed to urllib3 after a refactor to shared packages. github.com
• Behavior changed opentelemetry.sdk.processor.SimpleSpanProcessor
  Spans ended after shutdown() are now dropped instead of being sent to the exporter, and counted with error.type=already_shutdown. github.com
• Behavior changed opentelemetry.util.types.AttributeValue
  The AttributeValue type now accepts None, mixed sequences and mappings. Bytes attribute values in the SDK are passed through as-is instead of being decoded to a string. github.com
• Configuration changed
  Ruff default ruleset enabled for the repository in opentelemetry-api 1.45.0 github.com
• Signature changed opentelemetry.attributes.BoundedAttributes
  Was class BoundedAttributes(MutableMapping); now class BoundedAttributes(MutableMapping[str, types.AnyValue]). pypi.org
• Signature changed opentelemetry.attributes.BoundedAttributes.__deepcopy__
  Was def __deepcopy__(self, memo: dict) -> BoundedAttributes; now def __deepcopy__(self, memo: dict[int, Any]) -> BoundedAttributes. pypi.org
• Signature changed opentelemetry.attributes.BoundedAttributes.__init__
  Was def __init__(self, maxlen: int | None = None, attributes: types._ExtendedAttributes | None = None, immutable: bool = True, max_value_len: int | None = None, extended_attributes: bool = False); now def __init__(self, maxlen: int | None... pypi.org
• Signature changed opentelemetry.attributes.BoundedAttributes.copy
  Was def copy(self); now def copy(self) -> MutableMapping[str, types.AnyValue]. pypi.org
• Signature changed opentelemetry.metrics._Gauge.set
  Was def set(self, amount: int | float, attributes: Attributes | None = None, context: Context | None = None) -> None; now def set(self, amount: float, attributes: Attributes = None, context: Context | None = None) -> None. pypi.org

And 11 more in this version.

1.44.0

7 breaking changes, first published July 16, 2026.

• Removed
  The deprecated Events API and SDK are removed. Use LogRecord with the event_name field set instead. github.com
• Renamed opentelemetry.sdk._configuration
  Declarative configuration moves from opentelemetry.sdk._configuration into the opentelemetry-configuration package under the opentelemetry.configuration namespace. The sdk extra remains as an alias. github.com
• Behavior changed ExplicitBucketHistogramAggregation
  ExplicitBucketHistogramAggregation now raises ValueError when boundaries are not strictly increasing or finite. Code passing such boundaries must fix them. github.com
• Behavior changed ReadableLogRecord.context
  The context on exported log records is now an empty Context() instead of the original. Custom log exporters that read context must be updated. github.com
• Default changed ProcessResourceDetector
  process.command_args and process.command_line are no longer collected by default. Users who need them must pass include_command_args=True. github.com
• Configuration changed
  When OTEL_CONFIG_FILE is set, Python-implementation extensions via OTEL_PYTHON_* variables are bypassed. Settings must move into the declarative config file. github.com
• Signature changed EnvironmentGetter.get
  Environment snapshot caching is removed. Callers must now pass the mapping to read environment variables from as the first argument of EnvironmentGetter.get. github.com

1.43.0

15 breaking changes, first published June 24, 2026.

• Removed opentelemetry.propagate.entry_points
  opentelemetry.propagate.entry_points was removed in opentelemetry-api 1.43.0 pypi.org
• Behavior changed
  Entry points for opentelemetry_context are loaded only when OTEL_PYTHON_CONTEXT is defined; otherwise ContextVarsRuntimeContext is returned. Set the variable to keep using a custom context plugin. github.com
• Behavior changed EnvironmentGetter
  EnvironmentGetter now skips environment variable names that are not normalized, so code relying on them will no longer see those values. github.com
• Behavior changed EnvironmentSetter
  EnvironmentSetter now writes empty propagation names as _ instead of the empty name. github.com
• Signature changed opentelemetry.propagators.composite.CompositePropagator.__init__
  Was def __init__(self, propagators: typing.Sequence[textmap.TextMapPropagator]) -> None; now def __init__(self, propagators: collections.abc.Sequence[textmap.TextMapPropagator]) -> None. pypi.org
• Signature changed opentelemetry.propagators.textmap.DefaultGetter
  Was class DefaultGetter(Getter[typing.Mapping[str, CarrierValT]]); now class DefaultGetter(Getter[Mapping[str, CarrierValT]]). pypi.org
• Signature changed opentelemetry.propagators.textmap.DefaultGetter.get
  Was def get(self, carrier: typing.Mapping[str, CarrierValT], key: str) -> list[str] | None; now def get(self, carrier: Mapping[str, CarrierValT], key: str) -> list[str] | None. pypi.org
• Signature changed opentelemetry.propagators.textmap.DefaultGetter.keys
  Was def keys(self, carrier: typing.Mapping[str, CarrierValT]) -> list[str]; now def keys(self, carrier: Mapping[str, CarrierValT]) -> list[str]. pypi.org
• Signature changed opentelemetry.propagators.textmap.DefaultSetter
  Was class DefaultSetter(Setter[typing.MutableMapping[str, CarrierValT]]); now class DefaultSetter(Setter[MutableMapping[str, CarrierValT]]). pypi.org
• Signature changed opentelemetry.propagators.textmap.DefaultSetter.set
  Was def set(self, carrier: typing.MutableMapping[str, CarrierValT], key: str, value: CarrierValT) -> None; now def set(self, carrier: MutableMapping[str, CarrierValT], key: str, value: CarrierValT) -> None. pypi.org

And 5 more in this version.

1.42.0

78 breaking changes, first published May 19, 2026.

• Removed
  Python 3.9 is no longer supported; Python 3.10 or later is now required. Upgrade the interpreter before installing this release. github.com
• Renamed K8S_CONTAINER_CPU_LIMIT_UTILIZATION
  The semantic conventions bump to 1.41.1 changes the metric name for K8S_CONTAINER_CPU_LIMIT_UTILIZATION. Update dashboards and queries that use the old metric name. github.com
• Renamed K8S_CONTAINER_CPU_REQUEST_UTILIZATION
  The semantic conventions bump to 1.41.1 changes the metric name for K8S_CONTAINER_CPU_REQUEST_UTILIZATION. Update dashboards and queries that use the old metric name. github.com
• Behavior changed
  Resource detector entry points are now loaded only when listed in OTEL_EXPERIMENTAL_RESOURCE_DETECTORS. Detectors that were picked up automatically must now be listed there. github.com
• Behavior changed EnvironmentGetter
  EnvironmentGetter and EnvironmentSetter now use normalized environment variable names. Check any custom getter or setter that relies on the old names. github.com
• Behavior changed EnvironmentSetter
  EnvironmentGetter and EnvironmentSetter now use normalized environment variable names. Check any custom getter or setter that relies on the old names. github.com
• Behavior changed W3CBaggagePropagator.inject
  inject() now caps baggage at 180 entries, 4096 bytes per pair and 8192 bytes for the total header. Baggage that was previously sent in full may now be truncated. github.com
• Signature changed opentelemetry.attributes.BoundedAttributes.__init__
  Was def __init__(self, maxlen: Optional[int] = None, attributes: Optional[types._ExtendedAttributes] = None, immutable: bool = True, max_value_len: Optional[int] = None, extended_attributes: bool = False); now def __init__(self, maxlen... pypi.org
• Signature changed opentelemetry.baggage.clear
  Was def clear(context: Optional[Context] = None) -> Context; now def clear(context: Context | None = None) -> Context. pypi.org
• Signature changed opentelemetry.baggage.Context
  Was class Context(typing.Dict[str, object]); now class Context(dict[str, object]). pypi.org

And 68 more in this version.

1.41.0

8 breaking changes, first published April 9, 2026.

• Behavior changed
  Log records logged at Python's CRITICAL level are now exported with FATAL severity text instead of the previous value. github.com
• Default changed BatchLogRecordProcessor.schedule_delay_millis
  Logs may now be exported up to five times more often by default. Set the schedule delay explicitly (for example with OTEL_BLRP_SCHEDULE_DELAY) to keep the previous interval. github.com
• Signature changed opentelemetry.baggage.get_value
  Was def get_value(key: str, context: typing.Optional[Context] = None) -> 'object'; now def get_value(key: str, context: typing.Optional[Context] = None) -> object. pypi.org
• Signature changed opentelemetry.baggage.set_value
  Was def set_value(key: str, value: 'object', context: typing.Optional[Context] = None) -> Context; now def set_value(key: str, value: object, context: typing.Optional[Context] = None) -> Context. pypi.org
• Signature changed opentelemetry.context.get_value
  Was def get_value(key: str, context: typing.Optional[Context] = None) -> 'object'; now def get_value(key: str, context: typing.Optional[Context] = None) -> object. pypi.org
• Signature changed opentelemetry.context.set_value
  Was def set_value(key: str, value: 'object', context: typing.Optional[Context] = None) -> Context; now def set_value(key: str, value: object, context: typing.Optional[Context] = None) -> Context. pypi.org
• Signature changed opentelemetry.trace.propagation.get_value
  Was def get_value(key: str, context: typing.Optional[Context] = None) -> 'object'; now def get_value(key: str, context: typing.Optional[Context] = None) -> object. pypi.org
• Signature changed opentelemetry.trace.propagation.set_value
  Was def set_value(key: str, value: 'object', context: typing.Optional[Context] = None) -> Context; now def set_value(key: str, value: object, context: typing.Optional[Context] = None) -> Context. pypi.org

Check your code

These are the changes. To see which of them reach your code, scan a public repository, or have your coding agent call check_code with your manifest or lockfile over MCP. The API reads every change in every version, not only the newest. On Team and up, a fix pull request opens for the changes that reach a connected repository. Nothing merges or deploys.