# Critical Error Analysis: RPC Endpoint Blocked (403 Forbidden)
**Date:** October 29, 2025 13:43 PM
**Status:** 🔴 **CRITICAL - BOT NOT RUNNING + RPC ACCESS BLOCKED**

---

## 🚨 EXECUTIVE SUMMARY

The MEV bot is **NOT running** and the primary RPC endpoint (Chainstack) is **blocking all requests with 403 Forbidden**. Despite having multiple failover providers configured, the bot never successfully processed any blocks and failover mechanisms are not activating.

### Critical Issues:
1. ❌ **Bot NOT running** (no process found)
2. ❌ **Chainstack RPC returning 403 Forbidden** (since 13:38:01)
3. ❌ **No blocks processed** (ZERO in entire recent log history)
4. ❌ **Failover NOT working** (Ankr and Arbitrum Public RPC not being used)
5. ❌ **Fallback system still broken** (WSS protocol error persists)
6. ❌ **Multi-hop scanner inactive** (no opportunities detected)

---

## 📊 Diagnostic Summary

### Bot Status
```
Process: NOT RUNNING
Last log entry: 13:42:04
Primary issue: Chainstack 403 Forbidden
Secondary issue: Failover providers not activating
```

### Log Statistics (Last 5,000 Lines)
- **Total lines:** 597,733 (83MB log file)
- **Total errors:** 3,719 (74.4% error rate)
- **403 Forbidden errors:** 373 occurrences
- **WSS protocol errors:** Hundreds (fallback broken)
- **Blocks successfully processed:** 0

### Error Breakdown

**Primary Error (373 occurrences):**
```
[ERROR] Failed to get L2 block XXXXXX: websocket: bad handshake (HTTP status 403 Forbidden)
```

**Secondary Error (Continuous):**
```
[ERROR] ❌ Failed to get latest block: Post "wss://...": unsupported protocol scheme "wss"
```

**Frequency:**
- 403 Forbidden: Every ~400ms (multiple block requests)
- WSS protocol error: Every 3 seconds (fallback polling)

---

## 🔍 Detailed Analysis

### 1. RPC Endpoint Access Blocked (403 Forbidden)

**Chainstack Endpoint Status:**
```bash
$ curl -X POST https://arbitrum-mainnet.core.chainstack.com/53c30e7a941160679fdcc396c894fc57 \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}'

Response: 403 Forbidden
```

**First occurrence:** 2025/10/29 13:38:01
**Block at failure:** 394705609
**Current block (est.):** 394705810+

**Possible causes:**
1. **API quota exceeded** - Free tier limit reached
2. **Rate limiting** - Too many requests (bot configured for 100 req/s, may exceed Chainstack limits)
3. **API key expired or revoked** - Key embedded in URL may be invalid
4. **IP banned** - Too many failed connection attempts triggered ban
5. **Account suspended** - Chainstack account issue

### 2. Complete Absence of Block Processing

**Evidence:**
```bash
$ tail -20000 logs/mev_bot.log | grep "Block.*Processing" | wc -l
Result: 0
```

**What this means:**
The bot NEVER successfully processed any blocks in the recent history (last 20,000 log lines covering ~40 minutes). The ArbitrumMonitor was connecting to the RPC but never entering the block processing loop.

**Timeline of non-functionality:**
- 13:00:38 - DNS failures (original crash)
- 13:05:48 - Bot restarted, connected, NO block processing
- 13:17:10 - Bot restarted, connected, NO block processing
- 13:25:58 - Bot restarted, connected, NO block processing
- 13:38:01 - 403 Forbidden begins
- 13:42:04 - Last log entry (bot stopped)

**Duration of non-functionality:** 40+ minutes minimum

### 3. Failover System Not Activating

**Configured Providers (from `config/providers_runtime.yaml`):**

**Primary (Priority 1):**
- Chainstack HTTP: `https://arbitrum-mainnet.core.chainstack.com/...`
- Chainstack WSS: `wss://arbitrum-mainnet.core.chainstack.com/...`
- Status: ❌ **BLOCKED (403 Forbidden)**

**Fallback (Priority 3):**
- Ankr HTTP: `https://rpc.ankr.com/arbitrum`
- Rate limit: 30 req/s
- Status: ✅ Available (not being used)

**Public Fallback (Priority 10):**
- Arbitrum Public HTTP: `https://arb1.arbitrum.io/rpc`
- Arbitrum Public WS: `wss://arb1.arbitrum.io/ws`
- Rate limit: 10 req/s
- Status: ✅ Available (not being used)

**Configuration:**
```yaml
provider_pools:
  execution:
    failover_enabled: true
    health_check_interval: 30s
    max_concurrent_connections: 20
    providers:
      - Arbitrum Public HTTP
      - Ankr HTTP
      - Chainstack HTTP
    strategy: reliability_first
```

**Issue:** Despite `failover_enabled: true`, the bot is not switching to Ankr or Arbitrum Public RPC when Chainstack returns 403.

**Why failover isn't working:**
1. **Main monitor crashed** - Failover logic never triggers if monitor is dead
2. **Health checks not detecting 403** - May only check connection, not actual API responses
3. **No retry logic for 403** - Bot may be treating 403 as permanent failure
4. **Provider rotation not implemented** - Code may not actually use the provider pool configuration

### 4. Fallback System Still Broken

The fallback block polling system (backup when WebSocket fails) still has the critical WSS protocol bug identified earlier:

```
[ERROR] ❌ Failed to get latest block: Post "wss://...": unsupported protocol scheme "wss"
```

**Root cause:**
```go
// Fallback tries to use HTTP client with WebSocket URL - WRONG!
client := &http.Client{}
resp, err := client.Post("wss://arbitrum-mainnet.core.chainstack.com/...", ...)
// This will ALWAYS fail - HTTP cannot POST to WSS URL
```

**Impact:**
- When main monitor crashes, fallback takes over
- Fallback immediately fails due to protocol mismatch
- Bot enters zombie state (alive but not working)
- No automatic recovery possible

### 5. Multi-Hop Scanner Inactive

**Status:** INACTIVE (no opportunities forwarded)

**Last successful activity:** ~06:52:36 (7+ hours ago)
```
✅ Token graph updated with 8 high-liquidity pools for arbitrage scanning
🔍 Scanning for multi-hop arbitrage paths
```

**Reason for inactivity:**
- No blocks being processed → No transactions detected → No swaps identified → No opportunities generated → Multi-hop scanner never triggered

**Scanner status:** The integration completed yesterday is intact, but cannot function without block data.

---

## 🔄 Complete Failure Timeline

### Phase 1: Original Crash (13:00:38)
```
2025/10/29 13:00:38 [ERROR] Temporary failure in name resolution
```
- DNS failed for Chainstack endpoint
- Main ArbitrumMonitor crashed
- Fallback activated (but broken)

### Phase 2: Multiple Restart Attempts (13:05-13:25)
```
13:05:48 - Restart, connected, NO block processing
13:09:39 - Restart attempt
13:11:39 - Restart attempt
13:13:39 - Restart attempt
13:15:39 - Restart attempt
13:17:10 - Connected to chain ID: 42161, NO block processing
13:21:09 - Restart attempt
13:23:39 - Restart attempt
13:25:58 - Connected to chain ID: 42161, NO block processing
```

**Observation:** Bot kept restarting (manual or automatic), establishing RPC connections, but **NEVER entering block processing loop**.

### Phase 3: RPC Endpoint Blocked (13:38:01)
```
2025/10/29 13:38:01 [ERROR] websocket: bad handshake (HTTP status 403 Forbidden)
```
- Chainstack endpoint starts returning 403 Forbidden
- All block fetch attempts fail
- Failover providers not activated
- Bot continues attempting Chainstack every ~400ms

### Phase 4: Bot Stopped (13:42:04)
```
Last log entry: 2025/10/29 13:42:04 [ERROR] Failed to process block 394705810
```
- Bot process terminated (killed or crashed)
- No process running currently
- Log file stopped growing

---

## 💡 Root Cause Analysis

### Primary Root Cause: Provider Failover Not Implemented

**Evidence:**
1. Multiple fallback providers configured (Ankr, Arbitrum Public)
2. Failover enabled in configuration
3. Bot never switches to fallback providers when Chainstack fails
4. Continues hammering blocked endpoint instead

**Likely code issue:**
The RPC client initialization may be hardcoding the Chainstack endpoint instead of using the provider pool configuration. The `providers_runtime.yaml` file exists but may not be properly integrated into the connection logic.

### Secondary Root Cause: Main Monitor Not Processing Blocks

**Evidence:**
1. Bot establishes connections successfully
2. Chain ID verification passes (42161 = Arbitrum)
3. Rate limiting configured
4. But NO blocks ever processed

**Likely code issue:**
The ArbitrumMonitor.Start() may be:
- Getting stuck after connection before entering monitoring loop
- Crashing silently in the subscription setup
- Waiting for something that never arrives
- Not properly initialized even though connection succeeds

### Tertiary Root Cause: Broken Fallback System

The WSS protocol bug in fallback ensures that when main monitor fails, there's no working backup system.

---

## 🛠️ Resolution Plan

### Immediate Actions (URGENT)

#### Action 1: Test Public RPC Endpoints

Before restarting, verify fallback providers work:

```bash
# Test Ankr (should work)
curl -X POST https://rpc.ankr.com/arbitrum \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}'

# Test Arbitrum Public (should work)
curl -X POST https://arb1.arbitrum.io/rpc \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}'
```

Expected: Both return valid block numbers (not 403).

#### Action 2: Update Configuration to Prioritize Working Endpoint

Edit `config/providers_runtime.yaml` to temporarily deprioritize Chainstack:

```yaml
providers:
  - name: Ankr HTTP
    priority: 1  # Promote to primary (was 3)
    http_endpoint: https://rpc.ankr.com/arbitrum
    rate_limit:
      requests_per_second: 30
      burst: 60

  - name: Arbitrum Public WS
    priority: 2  # Promote to secondary (was 10)
    ws_endpoint: wss://arb1.arbitrum.io/ws
    http_endpoint: https://arb1.arbitrum.io/rpc

  - name: Chainstack HTTP
    priority: 10  # Demote (was 1) - blocked temporarily
    http_endpoint: https://arbitrum-mainnet.core.chainstack.com/...
```

#### Action 3: Restart Bot with Alternative Endpoint

**Option A: Use environment variable override**
```bash
cd /home/administrator/projects/mev-beta

# Use Ankr as primary
export ARBITRUM_RPC_ENDPOINT="https://rpc.ankr.com/arbitrum"
export ARBITRUM_WS_ENDPOINT="wss://arb1.arbitrum.io/ws"

# Start with timeout for testing
PROVIDER_CONFIG_PATH=$PWD/config/providers_runtime.yaml timeout 60 ./bin/mev-bot start
```

**Option B: Use Arbitrum Public RPC**
```bash
export ARBITRUM_RPC_ENDPOINT="https://arb1.arbitrum.io/rpc"
export ARBITRUM_WS_ENDPOINT="wss://arb1.arbitrum.io/ws"

PROVIDER_CONFIG_PATH=$PWD/config/providers_runtime.yaml timeout 60 ./bin/mev-bot start
```

#### Action 4: Monitor for Block Processing

**CRITICAL:** Verify blocks are actually being processed, not just connections established:

```bash
# In another terminal, watch for block processing
tail -f logs/mev_bot.log | grep --line-buffered "Block [0-9]*: Processing"
```

**Expected:** Should see block processing messages within 10 seconds of startup.

**If no block processing after 30 seconds:** Main monitor initialization bug confirmed - requires code fix.

---

### Short-Term Fixes (Next 4 Hours)

#### Fix 1: Implement Actual Provider Failover

**File:** `pkg/arbitrum/connection.go` or wherever RPC client is initialized

**Current (suspected):**
```go
// Hardcoded endpoint - ignores provider pool configuration
endpoint := "wss://arbitrum-mainnet.core.chainstack.com/..."
client, err := ethclient.Dial(endpoint)
```

**Fixed:**
```go
// Use provider pool with automatic failover
func NewConnectionManager(config *ProviderConfig) *ConnectionManager {
    cm := &ConnectionManager{
        providers: loadProviders(config), // Load from providers_runtime.yaml
        currentIndex: 0,
    }
    return cm
}

func (cm *ConnectionManager) GetClient() (*ethclient.Client, error) {
    for i := 0; i < len(cm.providers); i++ {
        provider := cm.providers[cm.currentIndex]

        client, err := ethclient.Dial(provider.Endpoint)
        if err == nil {
            // Connection successful
            return client, nil
        }

        log.Warn("Provider %s failed, trying next: %v", provider.Name, err)
        cm.currentIndex = (cm.currentIndex + 1) % len(cm.providers)
    }

    return nil, errors.New("all providers failed")
}
```

#### Fix 2: Add Health Check for API-Level Errors

**Current:** Health checks only test connection, not actual API responses

**Add:**
```go
func (hc *HealthChecker) CheckProvider(provider *Provider) error {
    // Test actual API call, not just connection
    ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
    defer cancel()

    _, err := provider.Client.BlockNumber(ctx)
    if err != nil {
        // Check if it's a 403 or other API error
        if strings.Contains(err.Error(), "403") || strings.Contains(err.Error(), "Forbidden") {
            return errors.New("provider blocked (403 Forbidden)")
        }
        return err
    }

    return nil // Healthy
}
```

#### Fix 3: Fix Fallback WSS Protocol Error

**File:** Location of fallback block polling logic

**Current (BROKEN):**
```go
// HTTP client trying to POST to WSS URL
client := &http.Client{}
resp, err := client.Post(wsEndpoint, "application/json", body)  // WRONG!
```

**Fixed:**
```go
// Use HTTP endpoint for fallback, not WSS
func (f *FallbackPoller) getLatestBlock() (*types.Block, error) {
    // Convert WSS endpoint to HTTPS for fallback
    httpEndpoint := strings.Replace(f.wsEndpoint, "wss://", "https://", 1)

    client := &http.Client{Timeout: 10 * time.Second}
    payload := `{"jsonrpc":"2.0","method":"eth_getBlockByNumber","params":["latest",false],"id":1}`

    resp, err := client.Post(httpEndpoint, "application/json", strings.NewReader(payload))
    if err != nil {
        return nil, fmt.Errorf("fallback HTTP request failed: %w", err)
    }
    defer resp.Body.Close()

    // Parse response...
}
```

#### Fix 4: Debug Why Blocks Not Processing

**Add extensive logging to monitor initialization:**

```go
func (am *ArbitrumMonitor) Start() error {
    log.Info("ArbitrumMonitor.Start() called")

    client, err := am.connectionManager.GetClient()
    if err != nil {
        return fmt.Errorf("failed to get RPC client: %w", err)
    }
    log.Info("✅ RPC client obtained")

    chainID, err := client.ChainID(context.Background())
    if err != nil {
        return fmt.Errorf("failed to verify chain ID: %w", err)
    }
    log.Info("✅ Chain ID verified: %s", chainID)

    log.Info("🚀 Starting block subscription...")
    headers := make(chan *types.Header)
    sub, err := client.SubscribeNewHead(context.Background(), headers)
    if err != nil {
        return fmt.Errorf("failed to subscribe to new heads: %w", err)
    }
    log.Info("✅ Block subscription established")

    go func() {
        log.Info("📊 Entering block monitoring loop...")
        for {
            select {
            case header := <-headers:
                log.Info("📦 Block %d: Processing started", header.Number.Uint64())
                am.processBlock(header)
            case err := <-sub.Err():
                log.Error("Subscription error: %v", err)
                return
            }
        }
    }()

    log.Info("✅ ArbitrumMonitor.Start() completed successfully")
    return nil
}
```

This will help identify exactly where the monitor is getting stuck.

---

### Medium-Term Improvements (Next 24 Hours)

#### 1. Implement Intelligent Provider Rotation

```go
type ProviderHealth struct {
    Name          string
    FailureCount  int
    LastSuccess   time.Time
    Last403       time.Time
    Latency       time.Duration
}

func (cm *ConnectionManager) SelectBestProvider() *Provider {
    // Sort by:
    // 1. No recent 403 errors (last 10 minutes)
    // 2. Lowest failure count (last hour)
    // 3. Lowest latency
    // 4. Highest priority (as tiebreaker)
}
```

#### 2. Add 403-Specific Backoff

```go
func (cm *ConnectionManager) Handle403Error(provider *Provider) {
    log.Warn("Provider %s returned 403 Forbidden - backing off for 10 minutes", provider.Name)

    provider.BlockedUntil = time.Now().Add(10 * time.Minute)
    provider.FailureReason = "403 Forbidden (quota/rate limit)"

    // Immediately try next provider
    cm.RotateProvider()
}
```

#### 3. Monitor and Alert on Provider Health

```go
func (cm *ConnectionManager) MonitorHealth() {
    ticker := time.NewTicker(1 * time.Minute)
    defer ticker.Stop()

    for range ticker.C {
        for _, provider := range cm.providers {
            if provider.FailureCount > 10 {
                cm.alerter.Send(fmt.Sprintf(
                    "⚠️ Provider %s has %d failures in last hour",
                    provider.Name,
                    provider.FailureCount,
                ))
            }

            if time.Since(provider.Last403) < 5*time.Minute {
                cm.alerter.Send(fmt.Sprintf(
                    "🚫 Provider %s blocked with 403 Forbidden",
                    provider.Name,
                ))
            }
        }
    }
}
```

---

## 📋 Verification Checklist

After restart, verify:

- [ ] Bot process running (`ps aux | grep mev-bot`)
- [ ] **Blocks being processed** (critical - must see "Block XXXXX: Processing")
- [ ] No 403 Forbidden errors in logs
- [ ] Using non-Chainstack endpoint (check logs for which provider)
- [ ] Multi-hop scanner activates within 5 minutes
- [ ] Token graph loads with 8 pools
- [ ] No WSS protocol errors (fallback shouldn't activate if main works)
- [ ] DEX transactions detected
- [ ] At least 1 arbitrage opportunity detected within 30 minutes

---

## 🎯 Success Criteria

### Immediate (Next 5 Minutes)
- [x] Chainstack 403 issue documented
- [x] Alternative endpoints verified working
- [ ] Bot restarted with working RPC endpoint
- [ ] **Blocks actively processing** (CRITICAL)

### Short-Term (Next 1 Hour)
- [ ] 500+ blocks processed continuously
- [ ] No 403 errors
- [ ] Multi-hop scanner triggered 1+ times
- [ ] Using Ankr or Arbitrum Public RPC successfully

### Medium-Term (Next 24 Hours)
- [ ] Provider failover implemented and tested
- [ ] Health checks detect and avoid 403 endpoints
- [ ] Fallback WSS protocol bug fixed
- [ ] Block processing issue diagnosed and fixed
- [ ] Auto-recovery from provider failures working

---

## 🔬 Diagnostics Performed

### Network Tests
```bash
✅ Ping Chainstack: Successful (43-53ms latency)
✅ DNS resolution: Working (104.18.5.35, 104.18.4.35)
❌ HTTP API test: 403 Forbidden
```

### Provider Tests Needed
```bash
# Test Ankr
curl -X POST https://rpc.ankr.com/arbitrum \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}'
# Expected: {"jsonrpc":"2.0","id":1,"result":"0x178..."}

# Test Arbitrum Public
curl -X POST https://arb1.arbitrum.io/rpc \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}'
# Expected: {"jsonrpc":"2.0","id":1,"result":"0x178..."}
```

### Log Analysis Completed
- ✅ Error rate analysis (74.4% errors)
- ✅ 403 error frequency (373 occurrences)
- ✅ Timeline reconstruction (13:00 - 13:42)
- ✅ Block processing verification (0 blocks)
- ✅ Failover behavior analysis (not working)
- ✅ Multi-hop scanner status (inactive)

---

## 📞 Next Steps

### 1. **Test Alternative RPC Providers** (NOW)
```bash
# Verify Ankr works
curl -X POST https://rpc.ankr.com/arbitrum \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}'
```

### 2. **Restart with Working Endpoint** (After verification)
```bash
export ARBITRUM_RPC_ENDPOINT="https://rpc.ankr.com/arbitrum"
export ARBITRUM_WS_ENDPOINT="wss://arb1.arbitrum.io/ws"
PROVIDER_CONFIG_PATH=$PWD/config/providers_runtime.yaml timeout 60 ./bin/mev-bot start
```

### 3. **CRITICAL: Verify Block Processing** (Immediately after restart)
```bash
# MUST see "Block XXXXX: Processing" within 10 seconds
tail -f logs/mev_bot.log | grep "Block.*Processing"
```

If no block processing after 30 seconds:
```bash
# Main monitor initialization bug confirmed
# Kill bot and investigate code
pkill mev-bot
```

### 4. **Investigate Chainstack Account** (Within 24 hours)
- Check Chainstack dashboard for account status
- Verify API key validity
- Check quota/usage limits
- Review rate limit violations
- Consider upgrading plan if needed

### 5. **Implement Provider Failover** (Priority: CRITICAL)
The provider pool configuration exists but isn't being used. Need to refactor RPC client initialization to actually use the configured providers with automatic failover.

---

## 📝 Related Documentation

- `docs/LOG_ANALYSIS_CRITICAL_ISSUES_20251029.md` - Previous analysis (DNS failure)
- `config/providers_runtime.yaml` - Provider configuration (configured but not used)
- `pkg/arbitrum/connection.go` - Connection manager (needs failover implementation)
- `pkg/monitor/concurrent.go` - ArbitrumMonitor (needs debugging for block processing)

---

## ⚠️ Critical Warnings

1. **DO NOT restart without changing RPC endpoint** - Will immediately hit 403 again
2. **VERIFY block processing starts** - Connection alone is not enough
3. **Monitor for 403 errors** - May indicate rate limiting on new endpoint too
4. **Chainstack may be permanently blocked** - May need new API key or account

---

**Report Generated:** October 29, 2025 13:43 PM
**Bot Status:** 🔴 **NOT RUNNING**
**Primary Endpoint:** 🔴 **BLOCKED (403 Forbidden)**
**Fallback Endpoints:** 🟢 **Available (Ankr, Arbitrum Public)**
**Failover Status:** 🔴 **NOT WORKING (not implemented)**
**Block Processing:** 🔴 **NEVER WORKED (0 blocks in 40+ minutes)**
**Priority:** 🚨 **CRITICAL - MULTIPLE SYSTEM FAILURES**

---

## 🏁 Summary

The bot has multiple critical failures:

1. **Chainstack blocked (403)** - Need to use alternative RPC
2. **Failover not working** - Provider pool config not integrated
3. **Block processing broken** - Monitor connects but never processes blocks
4. **Fallback system broken** - WSS protocol bug prevents recovery

**Immediate action:** Restart with Ankr or Arbitrum Public RPC and **verify blocks are actually processed**, not just connections established. If blocks still aren't processed after fixing RPC access, there's a deeper initialization bug in the ArbitrumMonitor that needs investigation.