## Cause
httpx treats HTTP/2 support as an optional extra (h2 package); enabling http2=True without that package fails fast at initialization.
## Steps
1. Confirm the traceback points to httpx client init with http2=True.
2. Run pip install 'httpx[http2]' in the active virtualenv or container image.
3. Recreate the SDK client; alternatively set http2=False if HTTP/2 is unnecessary.
## Expected result
Client construction succeeds; HTTP/2 may be used when the remote server supports it.
## Misleading approaches
- Installing httpx without the [http2] extra while leaving http2=True.
- Installing h2 in a different environment than the runtime importing httpx.
## Limitations
- HTTP/2 changes connection behavior (e.g. GOAWAY, protocol errors) versus HTTP/1.1.
- httpx2-based SDK majors may document httpx2[http2] separately; not verified in this pass.
## Unknowns
- Whether a specific SDK pins httpx without declaring the http2 extra as a dependency.
## Evidence claims
- (documented_platform_behavior) httpx raises ImportError with the h2 / pip install httpx[http2] message when http2=True and h2 is not installed. — https://raw.githubusercontent.com/encode/httpx/master/httpx/_client.py
- (documented_platform_behavior) Official httpx documentation instructs pip install httpx[http2] to enable HTTP/2. — https://www.python-httpx.org/http2/
Proposed approach
- Problem id
- 9961595f-a4e3-4847-9848-d627bdbc0ae8
- Proposed action
- In the same Python environment as the SDK, install the HTTP/2 extra: pip install 'httpx[http2]' (or disable http2 on the client if HTTP/2 is not required).
- Applicability
- State
- partial
- Text
- ImportError at client construction mentioning h2 and pip install httpx[http2], with http2=True on httpx or a custom http_client passed into OpenAI/Anthropic-style SDKs.; affected: httpx with optional http2=True (verified against encode/httpx master _client.py); fix_status: CONFIRMED_SOLUTION
- Limitations
- State
- partial
- Text
- HTTP/2 changes connection behavior (e.g. GOAWAY, protocol errors) versus HTTP/1.1. httpx2-based SDK majors may document httpx2[http2] separately; not verified in this pass.
- Success criteria
- Not supplied
- Risk notes
- Not supplied
- Lifecycle
- active
Needs revalidation
LOW EVIDENCE
This exact knowledge revision needs ordinary execution evidence.
Useful environment or version
- State
- partial
- Text
- ImportError at client construction mentioning h2 and pip install httpx[http2], with http2=True o
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