mev-beta/logs/ERROR_ANALYSIS_20251109.md

MEV Bot Error & Inconsistency Analysis

Date: November 9, 2025 Analysis Time: 04:31 UTC Container: mev-bot-production Total Log Lines Analyzed: 15,769+

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🚨 CRITICAL ISSUES FOUND

1. ❌ CRITICAL: Arbitrum Monitor Connection Failure

Error:

[ERROR] ❌ CRITICAL: Failed to create Arbitrum monitor:
failed to create contract executor:
failed to connect to Ethereum node:
websocket: bad handshake (HTTP status 403 Forbidden)

Impact: SEVERE - Bot is NOT using proper Arbitrum sequencer reader

Details:

• The bot attempted to connect to: wss://arbitrum-mainnet.core.chainstack.com/53c30e7a941160679fdcc396c894fc57
• Connection was rejected with HTTP 403 Forbidden
• This prevents the bot from using the proper ArbitrumMonitor with L2Parser

Current Status:

[ERROR] ❌ FALLBACK: Using basic block polling instead of proper sequencer reader
[INFO] ⚠️  USING FALLBACK BLOCK POLLING - This is NOT the proper sequencer reader!
[INFO] ⚠️  This fallback method has limited transaction analysis capabilities
[INFO] ⚠️  For full MEV detection, the proper ArbitrumMonitor with L2Parser should be used

Consequences:

• Limited transaction analysis capabilities
• May miss MEV opportunities that require L2-specific analysis
• Cannot detect certain types of arbitrage opportunities
• Reduced effectiveness compared to proper sequencer monitoring

Root Cause:

• Configuration mismatch between config.dev.yaml and .env
• config.dev.yaml specifies HTTP endpoint: https://arb1.arbitrum.io/rpc
• .env overrides with WSS endpoint that returns 403 Forbidden
• The WSS endpoint may require authentication or have access restrictions

Recommended Fix:

1. Use HTTP endpoint for contract executor: https://arb1.arbitrum.io/rpc
2. Or obtain proper credentials for the Chainstack WSS endpoint
3. Update configuration to use compatible RPC providers

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2. 🐛 BUG: Multi-Hop Arbitrage Always Uses Amount 0

Error Pattern:

[DEBUG] Processing swap event: amount0=-7196652813349979, amount1=24235863
[DEBUG] Starting multi-hop arbitrage scan for token [...] with amount 0

Occurrences: 803 instances (ALL multi-hop scans)

Impact: SEVERE - Arbitrage detection is broken

Details: Every time a swap event is detected with actual non-zero amounts, the subsequent multi-hop arbitrage scan is initiated with amount 0.

Examples:

Swap Event Amount0	Swap Event Amount1	Multi-hop Scan Amount	Result
-7196652813349979	24235863	0	❌ Wrong
-184770257309794794	622210434	0	❌ Wrong
189409592403453152	-637446655	0	❌ Wrong
356600000000000000	-1199728957	0	❌ Wrong
148930729359897857580	-42645234	0	❌ Wrong

Expected Behavior: The multi-hop arbitrage scan should use the actual swap amount (either amount0 or amount1 depending on direction) to calculate realistic arbitrage opportunities.

Actual Behavior: All scans use amount 0, which means:

• No realistic price impact calculations
• Cannot determine actual profitability
• Arbitrage detection will never find opportunities (amount 0 = no trade possible)

Code Issue Location: The swap event processing code is not correctly passing the swap amount to the multi-hop arbitrage scanner. It's likely defaulting to 0 or using the wrong variable.

Why This Matters:

• This is why Detected = 0 - The bot cannot find arbitrage opportunities with zero input amount
• Even if price discrepancies exist, they won't be detected because the calculation starts with 0

Recommended Fix:

// Current (broken):
scanner.StartMultiHopScan(token, 0)

// Should be:
scanner.StartMultiHopScan(token, actualSwapAmount)

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3. ⚠️ Configuration Inconsistency

Issue: Config file vs Environment variable mismatch

Config.dev.yaml:

arbitrum:
  rpc_endpoint: "https://arb1.arbitrum.io/rpc"
  ws_endpoint: ""

Environment (.env):

ARBITRUM_RPC_ENDPOINT=wss://arbitrum-mainnet.core.chainstack.com/...
ARBITRUM_WS_ENDPOINT=wss://arbitrum-mainnet.core.chainstack.com/...

Impact: MEDIUM - Causes confusion and connection failures

Details:

• Environment variables override config file
• Config specifies HTTP endpoint (working)
• .env specifies WSS endpoint (403 Forbidden)
• This inconsistency led to the Critical Issue #1

Recommended Fix: Align configuration sources to use the same, working endpoint.

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📊 ERROR FREQUENCY ANALYSIS

Errors by Type

Error Type	Count	Severity	Status
"arbitrage service disabled"	96	Low	✅ Resolved (startup only)
WebSocket 403 Forbidden	1	CRITICAL	❌ Active
Multi-hop amount=0 bug	803	CRITICAL	❌ Active
Missing pools.json	~50	Low	⚠️ Expected
Dashboard server closed	1	Low	✅ Normal shutdown
Metrics server closed	1	Low	✅ Normal shutdown

Critical Errors Timeline

03:32:56 UTC - Bot starts, connection to Arbitrum monitor fails 03:32:56 UTC - Falls back to basic block polling 03:33:01 UTC - First multi-hop scan with amount 0 (bug begins) 04:31:00 UTC - Still running in fallback mode (ongoing)

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🔍 INCONSISTENCIES DETECTED

1. Swap Detection vs Arbitrage Analysis Mismatch

Inconsistency:

• Swap Events Detected: 600+ with valid non-zero amounts
• Arbitrage Opportunities: 0 detected
• Multi-hop Scans: 803 initiated, ALL with amount 0

Analysis: The disconnect between detecting real swaps (with real amounts) and analyzing them for arbitrage (with zero amounts) explains why no opportunities are found.

Expected Flow:

Swap Event → Extract Amount → Analyze with Amount → Find Arbitrage

Actual Flow:

Swap Event → Extract Amount → Analyze with ZERO → Find Nothing ❌

2. Connection Success vs Monitor Failure

Inconsistency:

✅ RPC endpoints validated
❌ Failed to create Arbitrum monitor

Analysis:

• RPC validation passes (basic connectivity check)
• Arbitrum monitor creation fails (advanced sequencer connection)
• This suggests the endpoint works for basic queries but not for WebSocket subscriptions

3. Health Score vs Actual Functionality

Inconsistency:

• Health Score: 1/1 (Perfect)
• Actual Status: Running in fallback mode with broken arbitrage

Analysis: The health check system is not detecting:

• Fallback mode operation
• Zero-amount arbitrage bug
• Missing Arbitrum monitor

Recommendation: Enhance health checks to detect:

• Whether proper sequencer reader is active
• Whether arbitrage scans are using valid amounts
• Whether connection is in fallback mode

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🔧 DETAILED ERROR ANALYSIS

WebSocket Connection Failure Deep Dive

Attempted Connection:

wss://arbitrum-mainnet.core.chainstack.com/53c30e7a941160679fdcc396c894fc57

Response: HTTP 403 Forbidden

Possible Causes:

1. API Key Restriction: The endpoint may require additional authentication
2. Rate Limiting: Request may have been rate-limited
3. Geographic Restriction: IP address may be blocked
4. Incorrect Protocol: Endpoint may not support WSS connections
5. Service Limitation: Free tier may not support WebSocket subscriptions

Evidence:

• HTTP endpoint (https://) works for basic queries
• WSS endpoint (wss://) returns 403 Forbidden
• This pattern suggests WebSocket access is restricted

Testing:

# Test HTTP endpoint (likely works):
curl https://arbitrum-mainnet.core.chainstack.com/53c30e7a941160679fdcc396c894fc57

# Test WSS endpoint (returns 403):
wscat -c wss://arbitrum-mainnet.core.chainstack.com/53c30e7a941160679fdcc396c894fc57

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📈 IMPACT ASSESSMENT

Impact on MEV Detection

Component	Expected	Actual	Impact
Block Processing	✅ Real-time	✅ Real-time	None
Swap Detection	✅ Accurate	✅ Accurate	None
Arbitrage Analysis	✅ With amounts	❌ With zero	SEVERE
Opportunity Detection	✅ Find MEV	❌ Find nothing	SEVERE
Sequencer Monitoring	✅ L2Parser	❌ Fallback	HIGH

Performance Impact

• CPU Usage: 0.62% (efficient despite issues)
• Memory Usage: 0.8% (no leaks)
• Scan Performance: 35.48ms average (good)
• Detection Rate: 0% opportunities (broken)

Data Accuracy Impact

Metric	Status	Accuracy
Blocks Processed	✅ Accurate	100%
Swap Events	✅ Accurate	100%
Swap Amounts	✅ Accurate	100%
Arbitrage Input	❌ Wrong	0% (all zeros)
Opportunities	❌ Broken	0%

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🎯 ROOT CAUSE ANALYSIS

Root Cause #1: Configuration Error

What Happened:

1. Production deployment used .env file with WSS endpoint
2. WSS endpoint returns 403 Forbidden
3. Arbitrum monitor fails to initialize
4. Bot falls back to basic polling

Why It Happened:

• Environment variables override config file
• No validation that WSS endpoint is accessible
• No fallback RPC endpoint configured

How to Prevent:

• Validate all RPC endpoints during startup
• Test WebSocket connectivity before using
• Fail fast with clear error messages

Root Cause #2: Logic Bug in Arbitrage Scanner

What Happened:

1. Swap event detected with actual amounts
2. Swap amounts extracted correctly
3. Multi-hop scanner called with hardcoded 0
4. No opportunities found (can't arbitrage with 0)

Why It Happened:

• Code bug: Wrong variable passed to scanner
• Missing tests for swap event → arbitrage flow
• No validation that scan amount > 0

How to Prevent:

• Add unit tests for swap processing
• Add assertion: amount > 0 before scanning
• Add integration tests for full flow

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🚀 RECOMMENDED FIXES (Priority Order)

PRIORITY 1: Fix Multi-Hop Amount Bug

Severity: CRITICAL Impact: Enables arbitrage detection

Fix: Locate swap event processing code and ensure actual swap amounts are passed to multi-hop scanner.

File: Likely pkg/scanner/ or pkg/arbitrage/ Search for: StartMultiHopScan or multi-hop arbitrage scan Change: Pass actual swap amount instead of 0

Validation:

Before: "Starting multi-hop arbitrage scan for token X with amount 0"
After: "Starting multi-hop arbitrage scan for token X with amount 356600000000000000"

PRIORITY 2: Fix RPC Endpoint Connection

Severity: CRITICAL Impact: Enables proper Arbitrum sequencer monitoring

Fix Options:

Option A: Use HTTP Endpoint

# Update .env:
ARBITRUM_RPC_ENDPOINT=https://arb1.arbitrum.io/rpc
ARBITRUM_WS_ENDPOINT=  # Leave empty or remove

Option B: Fix WSS Endpoint

1. Contact Chainstack support
2. Verify API key has WebSocket permissions
3. Check account tier limitations
4. Test endpoint accessibility

Option C: Use Alternative Provider

# Free public endpoints:
ARBITRUM_RPC_ENDPOINT=https://arbitrum-one.publicnode.com
ARBITRUM_WS_ENDPOINT=wss://arbitrum-one.publicnode.com

PRIORITY 3: Add Validation & Health Checks

Severity: MEDIUM Impact: Prevents future issues

Add Checks:

1. Validate RPC endpoint accessibility on startup
2. Verify arbitrage scan amounts are non-zero
3. Detect fallback mode in health checks
4. Alert when running without proper monitor

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📝 SUMMARY

Critical Issues (Must Fix):

1. ❌ Multi-hop arbitrage always uses amount 0 (803 occurrences)
2. ❌ Arbitrum monitor connection fails (403 Forbidden)
3. ❌ Running in fallback mode (limited capabilities)

Impact:

• Current Detection Rate: 0% (broken)
• Expected Detection Rate: Should be > 0% with proper configuration
• Performance: Good (35ms scans)
• Stability: Excellent (no crashes)

Status:

✅ Bot is stable and running ✅ Data collection is accurate ❌ Arbitrage detection is broken ❌ Not using proper Arbitrum monitoring

Next Steps:

1. Fix multi-hop amount bug (code change required)
2. Fix RPC endpoint configuration (config change)
3. Restart bot and verify "with amount [non-zero]" in logs
4. Monitor for successful arbitrage detection

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Report generated from comprehensive log analysis Analysis covered 15,769+ log lines over 1 hour runtime Issues identified: 2 critical, 1 medium, 3 low