NationalSecurityAgency/ghidra · error · RuntimeError

No register mapper

Error message

No register mapper

What it means

Thrown as a RuntimeError by Extra.require_rm() in the gdb agent when the register_mapper attribute has not been set (is None). Analogous to error 172 but for register translation. The register_mapper is assigned during start_trace from arch.compute_register_mapper(language).

Source

Thrown at Ghidra/Debug/Debugger-agent-gdb/src/main/py/src/ghidragdb/commands.py:85

MODULE_PATTERN = MODULES_PATTERN + MODULE_KEY_PATTERN
SECTIONS_ADD_PATTERN = '.Sections'
SECTION_KEY_PATTERN = '[{secname}]'
SECTION_ADD_PATTERN = SECTIONS_ADD_PATTERN + SECTION_KEY_PATTERN


class Extra(object):
    def __init__(self) -> None:
        self.memory_mapper: Optional[arch.DefaultMemoryMapper] = None
        self.register_mapper: Optional[arch.DefaultRegisterMapper] = None

    def require_mm(self) -> arch.DefaultMemoryMapper:
        if self.memory_mapper is None:
            raise RuntimeError("No memory mapper")
        return self.memory_mapper

    def require_rm(self) -> arch.DefaultRegisterMapper:
        if self.register_mapper is None:
            raise RuntimeError("No register mapper")
        return self.register_mapper


class State(object):

    def __init__(self) -> None:
        self.reset_client()

    def require_client(self) -> Client:
        if self.client is None:
            raise gdb.GdbError("Not connected")
        return self.client

    def require_no_client(self) -> None:
        if self.client is not None:
            raise gdb.GdbError("Already connected")

    def reset_client(self) -> None:

View on GitHub (pinned to d5f144c24d)

Solutions

1. Call ghidra_trace_start successfully before any register-related command.
2. Verify STATE.trace.extra.register_mapper is not None before calling require_rm().
3. After ghidra_trace_disconnect, call ghidra_trace_start again before register operations.

Example fix

// before
ghidra_trace_connect('127.0.0.1:12345')
ghidra_trace_get_register('rax')  # fails: no trace started
// after
ghidra_trace_connect('127.0.0.1:12345')
ghidra_trace_start('myprogram')
ghidra_trace_get_register('rax')

def ensure_register_mapper() -> arch.DefaultRegisterMapper:
    if STATE.trace is None:
        raise RuntimeError('No active trace. Call ghidra_trace_start first.')
    rm = STATE.trace.extra.register_mapper
    if rm is None:
        raise RuntimeError('Register mapper not initialized. Trace may have failed to start.')
    return rm

def has_register_mapper() -> bool:
    return (
        STATE.trace is not None
        and STATE.trace.extra is not None
        and STATE.trace.extra.register_mapper is not None
    )

try:
    STATE.trace.extra.require_rm()
except RuntimeError as e:
    if 'No register mapper' in str(e):
        ghidra_trace_start()  # reinitialize trace
    raise

When it happens

Trigger: Calling any command that reads or writes registers before ghidra_trace_start has been called, or after the trace was reset. The require_rm() accessor checks for None and raises.

Common situations: Issuing register-read commands before starting the trace; trace initialization failed at create_trace before register_mapper assignment; disconnect and reconnect without re-starting the trace.

Related errors

• No memory mapper
• Inferiors[{infnum}] does not exist
• Cannot emulate a trace unless it's opened in the tool.
• Static program is not opened
• Trace is not opened in this tool

AI-assisted analysis of NationalSecurityAgency/ghidra@d5f144c24d (2026-08-14). Data as JSON: /api/errors/071726c4ca33a4fe. Report an issue: GitHub.