Fix clw-sandbox-timeout: Sandbox execution exceeded time limit

By James Park
OpenClaw intermediate Linux macOS Windows Cloud

1. Symptoms

When the clw-sandbox-timeout error occurs, you will observe the following symptoms in your OpenClaw environment:

Primary Symptoms:

  • The sandbox process terminates unexpectedly without completing its intended task
  • The OpenClaw CLI or API returns exit code 124, which indicates a timeout occurred
  • Error output contains the specific error code clw-sandbox-timeout

Typical Error Output:

Error: clw-sandbox-timeout
Message: Sandbox execution exceeded the configured time limit of 300 seconds
Process: openclaw-sandbox --id abc123 --timeout 300
Exit Code: 124

Behavioral Indicators:

  • The sandbox appears to hang indefinitely during execution
  • Partial results may be available but the process never reaches completion
  • Network requests or database connections initiated by the sandbox may remain open
  • Memory and CPU usage may plateau at a certain level before termination
  • Logs may show repeated heartbeat failures or missing progress updates

When It Occurs:

  • During long-running computational tasks within the sandbox
  • When processing large datasets or files
  • During integration tests that involve external service dependencies
  • When sandboxed code enters an infinite loop or waiting state
  • Under high system load where execution naturally takes longer

2. Root Cause

The clw-sandbox-timeout error occurs when the OpenClaw sandbox executor terminates a process because it exceeded the configured maximum execution time. Understanding the root causes helps in preventing this error.

Primary Root Causes:

  1. Insufficient Timeout Configuration The most common cause is setting a timeout value that is too short for the actual workload. When the sandbox execution time exceeds this threshold, OpenClaw forcefully terminates the process. This often happens when timeout values are set based on optimistic estimates rather than measured performance.

  2. Infinite Loops or Blocking Operations Sandboxed code that enters an infinite loop, recursive calls without proper termination, or blocking I/O operations will naturally exceed any reasonable timeout. This is particularly common when debugging complex algorithms or handling untrusted user code.

  3. External Service Latency Sandboxes that depend on external services (databases, APIs, message queues) may exceed timeouts when those services experience high latency, network issues, or temporary unavailability. The sandbox cannot complete its task while waiting for external responses.

  4. Resource Starvation Under system load, sandboxed processes may run significantly slower than expected, causing them to exceed timeouts that would be sufficient under normal conditions. CPU contention, memory pressure, or I/O bottlenecks can dramatically increase execution time.

  5. Incorrect Sandbox Configuration Misconfigured sandbox settings, such as setting timeout values in the wrong unit (seconds vs. milliseconds), using deprecated configuration keys, or conflicting timeout settings across multiple configuration layers.

Technical Background:

OpenClaw uses a watchdog process to monitor sandbox execution time. When the configured timeout is reached, the watchdog sends a SIGTERM signal to the sandbox process. If the process does not terminate gracefully within a grace period (typically 10 seconds), a SIGKILL signal is sent to forcefully terminate it.

Sandbox Process → Watchdog Timer → SIGTERM → Grace Period → SIGKILL
                    (timeout)        (soft)    (10 sec)     (hard)

3. Step-by-Step Fix

To resolve the clw-sandbox-timeout error, follow these steps in order:

Step 1: Identify the Current Timeout Configuration

First, determine what timeout value is currently configured for your sandbox:

# Check OpenClaw global configuration
openclaw config show

# Check sandbox-specific configuration
cat ~/.openclaw/config.yaml

# Check environment variables
echo $OPENCLAW_SANDBOX_TIMEOUT

Step 2: Increase the Timeout Value

Based on your analysis, increase the timeout to an appropriate value. The recommended approach is to set a timeout that is 2-3 times your expected execution time to account for variability.

Configuration via CLI:

# Set timeout to 600 seconds (10 minutes)
openclaw sandbox run --timeout 600 ./your-task

# Set timeout to 0 (no timeout, use with caution)
openclaw sandbox run --timeout 0 ./your-long-running-task

Configuration via config file (~/.openclaw/config.yaml):

Before:

sandbox:
  timeout: 60
  memory_limit: 512mb
  cpu_limit: 1

After:

sandbox:
  timeout: 600
  memory_limit: 512mb
  cpu_limit: 1

Configuration via environment variable:

export OPENCLAW_SANDBOX_TIMEOUT=600
openclaw sandbox run ./your-task

Step 3: Optimize Your Sandbox Code

If increasing the timeout is not feasible, optimize the sandboxed code to complete faster:

Example: Adding Progress Updates

# Before: Code without progress updates (appears hung)
def process_large_dataset(items):
    results = []
    for item in items:
        results.append(expensive_computation(item))
    return results

# After: Code with checkpoint-based cancellation support
def process_large_dataset(items, checkpoint_interval=100):
    results = []
    for i, item in enumerate(items):
        results.append(expensive_computation(item))
        # OpenClaw monitors for checkpoint signals
        if i % checkpoint_interval == 0:
            checkpoint(i, len(items))
    return results

Example: Implementing Timeout-Aware Operations

import signal

class TimeoutException(Exception):
    pass

def timeout_handler(signum, frame):
    raise TimeoutException("Operation timed out")

def run_with_timeout(func, args, timeout_seconds):
    signal.signal(signal.SIGALRM, timeout_handler)
    signal.alarm(timeout_seconds)
    try:
        result = func(*args)
        signal.alarm(0)  # Cancel the alarm
        return result
    except TimeoutException:
        # Clean up and report partial progress
        cleanup_partial_results()
        raise

Step 4: Handle External Service Dependencies

If your sandbox depends on external services, implement proper timeout handling and fallback mechanisms:

import requests
from requests.adapters import HTTPAdapter
from urllib3.util.retry import Retry

def create_resilient_session():
    session = requests.Session()
    retry_strategy = Retry(
        total=3,
        backoff_factor=1,
        status_forcelist=[429, 500, 502, 503, 504],
    )
    adapter = HTTPAdapter(max_retries=retry_strategy)
    session.mount("http://", adapter)
    session.mount("https://", adapter)
    return session

def fetch_data_with_timeout(url, timeout=30):
    session = create_resilient_session()
    response = session.get(url, timeout=timeout)
    response.raise_for_status()
    return response.json()

Step 5: Set Appropriate Timeout Hierarchies

Configure timeouts at multiple levels to ensure proper coverage:

Before:

# Only setting CLI timeout
openclaw sandbox run --timeout 300 ./task

After:

# Multiple timeout layers in config
sandbox:
  timeout: 600
  graceful_shutdown_seconds: 30
  hard_kill_seconds: 10

task_execution:
  per_step_timeout: 120
  total_timeout: 600

4. Verification

After applying the fix, verify that the sandbox executes successfully:

Basic Verification

# Run the sandbox with increased timeout
openclaw sandbox run --timeout 600 ./your-task

# Check exit code
echo $?

# Expected output: 0 (success)

Detailed Verification

# Run with verbose output to see timing information
openclaw sandbox run --timeout 600 --verbose ./your-task

# Check the execution log
openclaw sandbox logs --tail 100

# Verify sandbox completed within expected time
openclaw sandbox status --id <sandbox-id>

Test Script for Timeout Configuration

Create a verification script to ensure timeout settings are properly applied:

#!/bin/bash
# verify-timeout.sh

TIMEOUT_VALUE=$(openclaw config get sandbox.timeout)
echo "Current sandbox timeout: ${TIMEOUT_VALUE}s"

# Run a simple test task
START_TIME=$(date +%s)
openclaw sandbox run --timeout "${TIMEOUT_VALUE}" ./test-task
EXIT_CODE=$?
END_TIME=$(date +%s)

ELAPSED=$((END_TIME - START_TIME))
echo "Execution time: ${ELAPSED}s"
echo "Exit code: ${EXIT_CODE}"

if [ $EXIT_CODE -eq 0 ]; then
    echo "✓ Sandbox completed successfully"
    exit 0
else
    echo "✗ Sandbox failed with exit code ${EXIT_CODE}"
    exit 1
fi

Performance Monitoring

Monitor execution times to ensure timeouts remain appropriate:

# List recent sandbox executions with timing
openclaw sandbox list --limit 20 --format json | jq '.[] | {id, duration, status}'

# Check for timeout patterns
openclaw sandbox list --limit 100 --format json | jq '.[] | select(.status == "timeout") | {id, duration}'

5. Common Pitfalls

When fixing the clw-sandbox-timeout error, be aware of these common pitfalls:

Pitfall 1: Setting Timeout Too High

Problem: Setting an extremely high timeout (like 0 or 86400 seconds) masks underlying performance issues and can cause resource exhaustion.

Solution: Set timeouts based on measured performance with a reasonable safety margin (2-3x). If a task genuinely needs more than 30 minutes, consider breaking it into smaller chunks.

# Bad: No timeout, dangerous
openclaw sandbox run --timeout 0 ./task

# Good: Generous but reasonable timeout
openclaw sandbox run --timeout 3600 ./task

# Better: Chunked execution
openclaw sandbox run --timeout 300 ./task-part-1
openclaw sandbox run --timeout 300 ./task-part-2

Pitfall 2: Ignoring Partial Results

Problem: When a timeout occurs, any partial work is lost. Without proper checkpointing, you must restart from the beginning.

Solution: Implement periodic checkpoints to save progress:

# Bad: No checkpointing
def process_all(items):
    results = []
    for item in items:
        results.append(compute(item))
    return results

# Good: Checkpoint-based processing
def process_with_checkpoint(items, checkpoint_file):
    results = load_checkpoint(checkpoint_file) if exists(checkpoint_file) else []
    start_index = len(results)
    
    for i, item in enumerate(items[start_index:], start=start_index):
        results.append(compute(item))
        if i % 100 == 0:
            save_checkpoint(checkpoint_file, results)
    
    return results

Pitfall 3: Conflicting Timeout Configurations

Problem: Timeout values set in multiple places (CLI, config file, environment variable) can conflict, leading to unexpected behavior.

Solution: Understand the precedence and document your configuration:

# OpenClaw timeout precedence (highest to lowest):
# 1. Command-line arguments
# 2. Environment variables
# 3. Config file settings
# 4. Default values

# Verify which setting is actually applied
openclaw sandbox run --timeout 600 --dry-run ./task

Pitfall 4: Not Handling SIGTERM Gracefully

Problem: Sandbox processes that do not handle termination signals properly may leave resources in an inconsistent state.

Solution: Implement proper signal handling:

import signal
import sys

running = True

def signal_handler(signum, frame):
    global running
    print("Received termination signal, cleaning up...")
    running = False
    # Perform cleanup operations here
    save_partial_results()
    sys.exit(0)

signal.signal(signal.SIGTERM, signal_handler)
signal.signal(signal.SIGINT, signal_handler)

# Main execution loop
while running:
    process_next_item()

Pitfall 5: Forgetting Timeout Units

Problem: Some configurations expect milliseconds while others expect seconds, leading to a 1000x difference.

Solution: Always verify the expected unit and convert appropriately:

# CLI typically expects seconds
openclaw sandbox run --timeout 300  # 300 seconds = 5 minutes

# Some config formats use milliseconds
# Check the documentation for your config format

# Convert if needed
python3 -c "print(5 * 60 * 1000)"  # 5 minutes in milliseconds

The following errors are related to clw-sandbox-timeout and may occur in similar contexts:

clw-sandbox-crash The sandbox process terminated unexpectedly due to a crash (segmentation fault, abort, etc.) rather than a timeout. Unlike timeouts, crashes typically indicate bugs in the sandboxed code or resource corruption.

Error: clw-sandbox-crash
Message: Sandbox process exited with signal SIGSEGV
Exit Code: 139

clw-process-timeout A more specific timeout error indicating that a spawned child process exceeded its timeout, while the parent sandbox may still be running.

clw-resource-exceeded The sandbox exceeded resource limits (memory, CPU, disk space) rather than time limits. This can cause apparent timeouts if the process becomes extremely slow due to resource constraints.

clw-sandbox-failed A generic sandbox failure that encompasses various failure modes, including timeouts, crashes, and configuration errors.

clw-execution-timeout An alternative naming for timeout errors, used in different versions of OpenClaw. The fix is identical to clw-sandbox-timeout.

Connection-Related Timeouts

# Network timeout within sandbox
Error: clw-sandbox-timeout
Context: HTTP request to https://api.example.com/data
Timeout: 30 seconds

# Database query timeout
Error: clw-sandbox-timeout
Context: SQL query execution
Timeout: 60 seconds

Prevention Strategies for Related Errors:

  1. Monitor sandbox health metrics (CPU, memory, I/O) alongside timeout status
  2. Implement circuit breakers for external service calls
  3. Use exponential backoff for retry logic
  4. Set up alerts for repeated timeout patterns
  5. Review sandbox logs regularly to identify trends before they become critical
# Example: Monitoring script for timeout-related errors
#!/bin/bash
openclaw sandbox list --limit 100 --format json | \
  jq '.[] | select(.error_code | startswith("clw-") and contains("timeout"))' | \
  jq -s 'group_by(.timestamp | strftime("%Y-%m-%d")) | map({date: .[0].timestamp | strftime("%Y-%m-%d"), count: length})'
openclaw sandbox-timeout clw-error execution-timeout resource-limits