Environment variable {key} is deprecated, please use {new_ke

Error message

Environment variable {key} is deprecated, please use {new_key}

What it means

At startup sglang rewrites legacy SGL_-prefixed variables to SGLANG_. Any SGL_ name not covered by the explicit deprecation table triggers this generic warning and gets copied to the SGLANG_ equivalent.

Source

Thrown at python/sglang/srt/environ.py:1716

        note="DFlash now auto-enables the min-free-slots delay; unset this env. "
        "To override the threshold, use '--min-free-slots-delay'."
    ),
    "SGLANG_ENABLE_UNIFIED_RADIX_TREE": _DeprecatedEnv(
        note="The unified radix tree is the default tree cache now; unset this "
        "env. The field is still defined for legacy call sites."
    ),
}


def _handle_deprecated_envs():
    for old_name, deprecation in _DEPRECATED_ENVS.items():
        deprecation.apply(old_name)

    # Rewrite the legacy SGL_ prefix to SGLANG_ (names not covered above).
    for key, value in list(os.environ.items()):
        if key.startswith("SGL_") and key not in _DEPRECATED_ENVS:
            new_key = key.replace("SGL_", "SGLANG_", 1)
            warnings.warn(
                f"Environment variable {key} is deprecated, please use {new_key}"
            )
            os.environ[new_key] = value


def third_party_cache_defaults() -> Dict[str, str]:
    base = os.path.expanduser(envs.SGLANG_CACHE_DIR.get())
    return {
        "TRITON_CACHE_DIR": os.path.join(base, "triton"),
        "TORCHINDUCTOR_CACHE_DIR": os.path.join(base, "inductor"),
        "CUDA_CACHE_PATH": os.path.join(base, "nv"),
        # FlashInfer appends ".cache/flashinfer" to this base itself, so this
        # is the base dir rather than the final cache dir.
        "FLASHINFER_WORKSPACE_BASE": base,
    }


def redirect_third_party_caches():

View on GitHub (pinned to 0132848349)

Solutions

Search your environment/scripts for SGL_-prefixed names and rename them to SGLANG_
Verify the renamed SGLANG_ var is actually a recognized setting (check sglang.srt.environ)
Delete stale SGL_ vars that no longer correspond to any setting

Example fix

# before
export SGL_RADIX_CACHE_AGE=3600
# after
export SGLANG_RADIX_CACHE_AGE=3600

Defensive patterns

Strategy: validation

Validate before calling

legacy = [k for k in os.environ if k.startswith("SGL_")]
for k in legacy:
    os.environ["SGLANG_" + k[4:]] = os.environ.pop(k)

Prevention

Namespace-check env stanzas in CI
Avoid defining unrelated vars starting with SGL_

When it happens

Trigger: Having any environment variable starting with SGL_ that is not in _DEPRECATED_ENVS when the sglang runtime initializes.

Common situations: Old launch scripts exporting SGL_* flags; base images from earlier releases; accidentally defining an unrelated variable whose name happens to start with SGL_.

Related errors

AI-assisted analysis of sgl-project/sglang@0132848349 (2026-08-28). Data as JSON: /api/errors/12bf4c106de3d95e. Report an issue: GitHub.