NationalSecurityAgency/ghidra · error · ValueError

Cannot write Value: {schema}, {value}, {type(value)}

Error message

Cannot write Value: {schema}, {value}, {type(value)}

What it means

Raised by Client._write_value() when serializing a Value and the given schema matches none of the handled writer branches (bool/byte/char/short/int/long/str/bytes/address/range/object and the *_ARR arrays). This means either the schema itself is unrecognized or the value does not match a branch the writer knows about — the pair cannot be placed on the wire.

Source

Thrown at Ghidra/Debug/Debugger-rmi-trace/src/main/py/src/ghidratrace/client.py:854

    @staticmethod
    def _try_write_array(to: bufs.Value, value: Iterable,
                         schema: Optional[sch.Schema]) -> None:
        if schema == sch.BOOL_ARR:
            to.bool_arr_value.arr[:] = value
            return
        elif schema == sch.SHORT_ARR:
            to.short_arr_value.arr[:] = value
            return
        elif schema == sch.INT_ARR:
            to.int_arr_value.arr[:] = value
            return
        elif schema == sch.LONG_ARR:
            to.long_arr_value.arr[:] = value
            return
        elif schema == sch.STRING_ARR:
            to.string_arr_value.arr[:] = value
            return
        raise ValueError(
            f"Cannot write Value: {schema}, {value}, {type(value)}")

    @staticmethod
    def _write_parameter(to: bufs.MethodParameter, p: RemoteParameter) -> None:
        to.name = p.name
        to.type.name = p.schema.name
        to.required = p.required
        Client._write_value(to.default_value, p.default)
        to.display = p.display
        to.description = p.description

    @staticmethod
    def _write_parameters(to: RCFC[bufs.MethodParameter],
                          parameters: Iterable[RemoteParameter]) -> None:
        for i, p in enumerate(parameters):
            to.add()
            Client._write_parameter(to[i], p)

View on GitHub (pinned to d5f144c24d)

Solutions

1. Use only the sch.* constants defined in sch.py for wire values.
2. Ensure client and server share the same ghidratrace version.
3. Avoid ANY/UNSPECIFIED as a concrete value schema; pick the precise scalar/array/object schema.

Example fix

# before
to_value(value, sch.Schema('WIDGET'))
# after
from ghidratrace import sch
to_value(value, sch.STRING)  # use a supported schema constant

import ghidratrace.sch as sch
WRITABLE = {sch.BOOL, sch.BYTE, sch.CHAR, sch.SHORT, sch.INT, sch.LONG,
            sch.STRING, sch.BYTE_ARR, sch.ADDRESS, sch.RANGE, sch.OBJECT,
            sch.BOOL_ARR, sch.CHAR_ARR, sch.SHORT_ARR, sch.INT_ARR,
            sch.LONG_ARR, sch.STRING_ARR}
if schema not in WRITABLE:
    raise TypeError(f'Unwritable schema {schema}')

def is_writable_schema(s) -> bool:
    import ghidratrace.sch as sch
    return s in {sch.BOOL, sch.BYTE, sch.CHAR, sch.SHORT, sch.INT, sch.LONG,
                 sch.STRING, sch.BYTE_ARR, sch.ADDRESS, sch.RANGE, sch.OBJECT,
                 sch.BOOL_ARR, sch.CHAR_ARR, sch.SHORT_ARR, sch.INT_ARR,
                 sch.LONG_ARR, sch.STRING_ARR}

When it happens

Trigger: Passing a Schema with a custom/unknown name, passing a schema constant that was removed/renamed between versions, or a value whose schema is UNSPECIFIED/ANY (which have no writer).

Common situations: Version mismatch between client and server (new schema on one side, old writer on the other); constructing a Schema('CUSTOM') by hand; a method returning a value typed as ANY.

Related errors

• Cannot convert: {value:r}
• Object/proxy has neither id nor path!: {}
• The parameter '%s' of method '%s' refers to a non-existent s
• Cannot get schema for {annotation}
• Could not read value: {}

AI-assisted analysis of NationalSecurityAgency/ghidra@d5f144c24d (2026-08-14). Data as JSON: /api/errors/1943313e86860ad7. Report an issue: GitHub.