NationalSecurityAgency/ghidra · error · RuntimeError

Trace already started

Error message

Trace already started

What it means

Raised by State.require_no_trace() when the Ghidra debug agent already has an active Trace object (STATE.trace is not None). The guard enforces single-trace ownership: only one trace may exist per connected client at a time. This prevents overlapping start_trace calls from corrupting the trace lifecycle and the '_ghidra_tracing' convenience variable.

Source

Thrown at Ghidra/Debug/Debugger-agent-dbgeng/src/main/py/src/ghidradbg/commands.py:139

            raise RuntimeError("Not connected")
        return self.client

    def require_no_client(self) -> None:
        if self.client != None:
            raise RuntimeError("Already connected")

    def reset_client(self) -> None:
        self.client: Optional[Client] = None
        self.reset_trace()

    def require_trace(self) -> Trace[Extra]:
        if self.trace is None:
            raise RuntimeError("No trace active")
        return self.trace

    def require_no_trace(self) -> None:
        if self.trace != None:
            raise RuntimeError("Trace already started")

    def reset_trace(self) -> None:
        self.trace: Optional[Trace[Extra]] = None
        util.set_convenience_variable('_ghidra_tracing', "false")
        self.reset_tx()

    def require_tx(self) -> Tuple[Trace, Transaction]:
        trace = self.require_trace()
        if self.tx is None:
            raise RuntimeError("No transaction")
        return trace, self.tx

    def require_no_tx(self) -> None:
        if self.tx != None:
            raise RuntimeError("Transaction already started")

    def reset_tx(self) -> None:
        self.tx: Optional[Transaction] = None

View on GitHub (pinned to d5f144c24d)

Solutions

1. Call ghidra_trace_stop() (or ghidra_trace_disconnect()) before starting a new trace, so STATE.trace is reset to None.
2. If you do not care about preserving the current trace, use ghidra_trace_restart(name) instead of ghidra_trace_start — it closes and resets the existing trace first (commands.py:282-290).
3. Check the '_ghidra_tracing' convenience variable (set false by reset_trace) before issuing start; if it is 'true', tear down first.

Example fix

// before
ghidra_trace_start('myapp')   # fails if a trace already exists
ghidra_trace_start('myapp')

// after
if STATE.trace is not None:
    ghidra_trace_stop()
ghidra_trace_start('myapp')
# or simply:
ghidra_trace_restart('myapp')

from ghidradbg.commands import STATE
if getattr(STATE, 'trace', None) is not None:
    ghidra_trace_stop()   # tear down before starting a new one

def trace_is_idle() -> bool:
    from ghidradbg.commands import STATE
    return getattr(STATE, 'trace', None) is None

try:
    ghidra_trace_start(name)
except RuntimeError as e:
    if 'Trace already started' in str(e):
        ghidra_trace_restart(name)   # or stop then start
    else:
        raise

When it happens

Trigger: Calling ghidra_trace_start(name) a second time without first calling ghidra_trace_stop() or ghidra_trace_disconnect(); calling start_trace() directly while a prior create_trace() result still lives in STATE.trace; invoking any command that wraps require_no_trace() (ghidra_trace_start at commands.py:271) when a trace is already live.

Common situations: Re-running a trace script in the same dbgeng/cdb/WinDbg session after the first run completed but ghidra_trace_stop was skipped; lingering trace after a debugger crash or abrupt disconnect where reset_trace() never fired; batch scripts that loop create-and-trace without teardown.

Related errors

• No transaction
• Transaction already started
• 'ghidra_trace_connect': missing required argument 'address'
• Invalid argument: {key_list[0]}
• Usage: ghidra trace disassemble ADDRESS

AI-assisted analysis of NationalSecurityAgency/ghidra@d5f144c24d (2026-08-14). Data as JSON: /api/errors/867cea829ff5a13f. Report an issue: GitHub.