vllm-project/vllm · error · RuntimeError

vLLM failed to compile the model. The most likely reason for

Error message

vLLM failed to compile the model. The most likely reason for this is that a previous compilation failed, leading to a corrupted compilation artifact. We recommend trying to remove ~/.cache/vllm/torch_compile_cache and try again to see the real issue.

What it means

vLLM compiles each partitioned graph through torch inductor's compile_fx with a monkey-patched inner compile that records a cache hash (hash_str). When the compilation cache is enabled but hash_str is still None after compile_fx returns, vLLM could not obtain a cache key for the compiled artifact. This almost always means a previous failed compilation left a corrupted artifact in ~/.cache/vllm/torch_compile_cache, which now blocks the cache-hash path and hides the real underlying error.

Source

Thrown at vllm/compilation/compiler_interface.py:647

            if saved_tracing_context is not None:
                torch._guards._TLS.tracing_context = None

                def _restore_tracing_context():
                    torch._guards._TLS.tracing_context = saved_tracing_context

                stack.callback(_restore_tracing_context)

            compiled_graph = compile_fx(
                graph,
                example_inputs,
                inner_compile=hijacked_compile_fx_inner,
                config_patches=current_config,
            )

        # Turn off the checks if we disable the compilation cache.
        if is_compile_cache_enabled(compiler_config):
            if hash_str is None:
                raise RuntimeError(
                    "vLLM failed to compile the model. The most "
                    "likely reason for this is that a previous compilation "
                    "failed, leading to a corrupted compilation artifact. "
                    "We recommend trying to "
                    "remove ~/.cache/vllm/torch_compile_cache and try again "
                    "to see the real issue. "
                )
            assert file_path is not None, (
                "failed to get the file path of the compiled graph"
            )
        return compiled_graph, (hash_str, file_path)

    def load(
        self,
        handle: Any,
        graph: fx.GraphModule,
        example_inputs: list[Any],
        graph_index: int,

View on GitHub (pinned to c794754062)

Solutions

Remove the compilation cache: rm -rf ~/.cache/vllm/torch_compile_cache, then rerun to surface the real error.
If it recurs, disable the compile cache to bypass artifact loading (e.g. set compilation_config.compile_cache_config or VLLM_DISABLE_COMPILE_CACHE=1 / run with -O0 eager) and inspect the underlying failure.
Check for interrupted prior runs (OOM, SIGKILL, full disk in $HOME/.cache) that could have written partial artifacts.
Report the underlying traceback to vLLM if the error persists on a clean cache.

Example fix

# before
python -m vllm.entrypoints.openai.api_server --model meta-llama/Llama-3-8B # RuntimeError: vLLM failed to compile the model...
# after
rm -rf ~/.cache/vllm/torch_compile_cache
python -m vllm.entrypoints.openai.api_server --model meta-llama/Llama-3-8B

Defensive patterns

Strategy: retry

Validate before calling

import shutil, pathlib
cache = pathlib.Path.home() / ".cache/vllm/torch_compile_cache"
if cache.exists():
    bad = []
    for f in cache.rglob('*'):
        try:
            if f.is_file() and f.stat().st_size == 0:
                bad.append(f)
        except OSError:
            bad.append(f)
    if bad:
        shutil.rmtree(cache)  # start clean before serving

Try / catch

try:
    llm = LLM(model=..., compilation_config=CompilationConfig(mode='VLLM_COMPILE'))
except RuntimeError as e:
    if 'corrupted compilation artifact' in str(e):
        shutil.rmtree(pathlib.Path.home() / '.cache/vllm/torch_compile_cache', ignore_errors=True)
        llm = LLM(model=..., compilation_config=CompilationConfig(mode='VLLM_COMPILE'))  # one retry
    else:
        raise

Prevention

Wipe ~/.cache/vllm/torch_compile_cache after upgrading vLLM or PyTorch
Avoid killing the process mid-compilation; use graceful shutdown
Pin one cache directory per vllm/torch version pair in CI

When it happens

Trigger: Running with CompilationConfig mode=VLLM_COMPILE (piecewise compilation) or any mode where is_compile_cache_enabled(compiler_config) is True, and compile_fx returning without the hijacked inner compile having captured hash_str/file_path (e.g. an inductor cache-hit path from a stale/corrupt entry, or an inner error swallowed by cache logic).

Common situations: A previous run crashed or was killed mid-compilation; upgrading vLLM or PyTorch while reusing an old torch_compile_cache; running with default compilation config (-O3) after disk-full or permission issues corrupted cache files.

Related errors

AI-assisted analysis of vllm-project/vllm@c794754062 (2026-08-14). Data as JSON: /api/errors/891e731e7dd4b2bc. Report an issue: GitHub.