skylot/jadx · error · JadxOverflowException

Regions stack size limit reached

Error message

Regions stack size limit reached

What it means

Thrown by RegionStack.push once the region-nesting depth exceeds REGIONS_STACK_LIMIT (hard-coded 1000). RegionStack tracks the nesting of regions (loops, ifs, try/catch) during region making; exceeding 1000 levels indicates pathologically deep nesting that would otherwise overflow the JVM stack. Like 181 it is a JadxOverflowException meant to fail a single method gracefully.

Source

Thrown at jadx-core/src/main/java/jadx/core/dex/visitors/regions/maker/RegionStack.java:67

			return "Region: " + region + ", exits: " + exits;
		}
	}

	private final Deque<State> stack;
	private State curState;

	public RegionStack(MethodNode mth) {
		if (DEBUG) {
			LOG.debug("New RegionStack: {}", mth);
		}
		this.stack = new ArrayDeque<>();
		this.curState = new State();
	}

	public void push(IRegion region) {
		stack.push(curState);
		if (stack.size() > REGIONS_STACK_LIMIT) {
			throw new JadxOverflowException("Regions stack size limit reached");
		}
		curState = curState.copyWith(region);
		if (DEBUG) {
			LOG.debug("Stack push: {}: {}", size(), curState);
		}
	}

	public void pop() {
		curState = stack.pop();
		if (DEBUG) {
			LOG.debug("Stack  pop: {}: {}", size(), curState);
		}
	}

	/**
	 * Add boundary(exit) node for current stack frame
	 *
	 * @param exit boundary node, null will be ignored

View on GitHub (pinned to e738a26571)

Solutions

1. Upgrade jadx; region nesting has been bounded and refactored over releases.
2. Report the sample so the cap or the nesting logic can be revisited.
3. Exclude the affected method/class and continue the batch.
4. Catch JadxOverflowException around per-method decompilation when using jadx as a library.

Example fix

// before
JadxDecompiler d = new JadxArgs(); ... d.parseClass(...).decompile();
// after
try { cls.decompile(); }
catch (JadxOverflowException e) { LOG.warn("skip {}: {}", cls, e.getMessage()); }

try {
    cls.decompile();
} catch (JadxOverflowException e) {
    if (e.getMessage().contains("Regions stack size limit")) {
        cls.addError("region nesting too deep", e);
    } else { throw e; }
}

When it happens

Trigger: Decompiling a method whose region structure nests more than 1000 levels deep, which happens when the block graph has an extremely long chain of nested scopes (loops inside loops, ifs inside try/catch) before the maker can flatten them.

Common situations: Obfuscated bytecode that inserts thousands of synthetic nested scopes, generated code, or recursive-descent generated state machines. Rare in normal app code; common against hardened/packed targets.

Related errors

• Regions count limit reached at block {}
• Bad name for type variable: {}
• Can't parse type: {}, unexpected: {}
• No inner type found: {}
• Unexpected inner type found: {}

AI-assisted analysis of skylot/jadx@e738a26571 (2026-08-14). Data as JSON: /api/errors/319de2da4ebcc4bf. Report an issue: GitHub.