NationalSecurityAgency/ghidra · error · IllegalArgumentException

Cannot advance a negative number

Error message

Cannot advance a negative number

What it means

Thrown by AbstractStep.advance(long steps) when steps < 0. advance() only grows a step's tick count, so a negative argument (a request to shrink via advance) is rejected; use rewind() to reduce the count.

Source

Thrown at Ghidra/Debug/Framework-TraceModeling/src/main/java/ghidra/trace/model/time/schedule/AbstractStep.java:86

		return tickCount;
	}

	@Override
	public long getPatchCount() {
		return 0;
	}

	@Override
	public abstract AbstractStep clone();

	/**
	 * Add to the count of this step
	 * 
	 * @param steps the count to add
	 */
	public void advance(long steps) {
		if (steps < 0) {
			throw new IllegalArgumentException("Cannot advance a negative number");
		}
		long newCount = tickCount + steps;
		if (newCount < 0) {
			throw new IllegalArgumentException("Total step count exceeds LONG_MAX");
		}
		this.tickCount = newCount;
	}

	@Override
	public long rewind(long steps) {
		if (steps < 0) {
			throw new IllegalArgumentException("Cannot rewind a negative number");
		}
		long diff = this.tickCount - steps;
		this.tickCount = Long.max(0, diff);
		return -diff;
	}

View on GitHub (pinned to d5f144c24d)

Solutions

1. Route reductions through rewind(): if (steps >= 0) advance(steps); else rewind(-steps).
2. Ensure the delta passed to advance is non-negative at the call site.
3. Prefer TraceSchedule-level APIs that handle direction.

Example fix

// before
step.advance(delta); // delta < 0 -> exception

// after
if (delta >= 0) step.advance(delta);
else step.rewind(-delta);

if (delta >= 0) step.advance(delta);
else step.rewind(-delta);

static boolean validAdvance(long steps) { return steps >= 0; }

When it happens

Trigger: Calling step.advance(n) with a negative n, often because a computed delta was negative.

Common situations: Reusing the same delta for both forward and backward movement; off-by-one in schedule arithmetic producing a negative increment.

Related errors

• Cannot step a negative number
• Total step count exceeds LONG_MAX
• Cannot rewind a negative number
• operandIndex
• Memory addresses cannot be associated with a thread

AI-assisted analysis of NationalSecurityAgency/ghidra@d5f144c24d (2026-08-14). Data as JSON: /api/errors/f0aece1a58a25df6. Report an issue: GitHub.