unslothai/unsloth · error · ValueError

llama-server does not accept the spaces around '{token[:64]}

Error message

llama-server does not accept the spaces around '{token[:64]}': write it as '{flag}'

What it means

ValueError from llama_server_args.py:300 — a flag token carries leading/trailing whitespace (token != token.strip()). _flag_name strips before lookup, so a quoted '--top-k ' passed the denylist and arity walk as --top-k but would reach the child with the space attached; llama.cpp looks up the WHOLE token and answers 'error: invalid argument: --top-k' (measured on b10342), naming a flag that looks correct in the log. Only flag-shaped tokens are checked — values (chat templates, grammars) may legitimately end in whitespace.

Source

Thrown at studio/backend/core/inference/llama_server_args.py:300

            # model path: that is the one thing the -m / --model denial exists to
            # prevent, and it would sidestep the native-path lease as well.
            if pending_values <= 0:
                raise ValueError(
                    "extra llama-server args cannot contain a bare value "
                    f"('{token[:64]}'); every value must follow its flag"
                )
            pending_values -= 1
            if pending_two_value > 0:
                pending_two_value -= 1
        elif token != token.strip():
            # _flag_name strips before it looks anything up, so a quoted "--top-k "
            # passed the denylist and the arity walk as --top-k and then went to the
            # child with the space still on it. llama.cpp looks the whole token up,
            # so it answers "error: invalid argument: --top-k" (measured on b10342),
            # naming a flag that looks correct in the log. Only flag-shaped tokens:
            # a VALUE may legitimately end in whitespace, a chat template or a
            # grammar being the obvious ones.
            raise ValueError(
                f"llama-server does not accept the spaces around '{token[:64]}': "
                f"write it as '{flag}'"
            )
        elif "=" in token:
            # llama.cpp looks the WHOLE token up in its option map, folding only the
            # underscore spelling, so "--top-k=20" is not "--top-k" with a value: it
            # is an argument it has never heard of. Measured on b10342 and b10360,
            # where --top-k=20, --ctx-size=4096 and --flash-attn=on each exit with
            # "error: invalid argument". Accepting the GNU spelling here meant the
            # switch tore down the resident model and the child then refused to
            # start, so it is refused while it is still a 400 with somewhere to go.
            # Splitting it here would be a guess: for a switch the value is not one,
            # and this module cannot know an ordinary flag's arity.
            value = token.partition("=")[2]
            raise ValueError(
                f"llama-server does not read an attached value: write '{flag}' and "
                f"'{value[:32]}' as two separate arguments, not '{token[:64]}'"
            )

View on GitHub (pinned to 203007d190)

Solutions

  1. Strip flag tokens before submitting: [t if not t.startswith('-') else t.strip() for t in args] — the error message itself tells you the correct spelling.
  2. Fix the producer: don't pad flag strings when building argv; only values may carry whitespace.
  3. Use shlex.split on a properly quoted command line so spaces inside quotes stay on values, not flags.

Example fix

# before
extra_args = ["--top-k ", "40"]  # trailing space on the flag

# after
extra_args = ["--top-k", "40"]
Defensive patterns

Strategy: validation

Validate before calling

extra_args = [t.strip() if t.startswith('-') and '=' not in t else t for t in extra_args]

Type guard

def flag_is_clean(token) -> bool:
    return not token.startswith('-') or token == token.strip()

Try / catch

try:
    validate_extra_args(args)
except ValueError as e:
    if "spaces around" in str(e):
        args = [t if not t.startswith('-') else t.strip() for t in args]
        validate_extra_args(args)
    else:
        raise

Prevention

When it happens

Trigger: Passing a quoted flag with an accidental trailing/leading space: '--top-k ' or ' --flash-attn', typically from template-built arg strings or copy-paste where the space before a closing quote survives.

Common situations: f-string / shell building like f"--top-k {k} " then splitting; copy-pasting from docs with stray spaces; JSON config values with trailing whitespace around flag names.

Related errors

AI-assisted analysis of unslothai/unsloth@203007d190 (2026-08-15). Data as JSON: /api/errors/cdd360f6bb0f1011. Report an issue: GitHub.