proxmox/docs/06-besu/VALIDATOR_TXPOOL_CONFIGURATION_FIX.md

Validator Transaction Pool Configuration Fix

Last Updated: 2026-01-31
Document Version: 1.0
Status: Active Documentation

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Date: 2025-01-20
Status: ✅ CONFIGURATION UPDATED

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Summary

Identified and fixed the root cause of empty blocks: validators were missing transaction pool configuration, preventing them from accepting and including transactions in blocks.

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Problem Identified

Symptoms

• Validators producing empty blocks (0 transactions)
• Transactions accepted by RPC but not included in blocks
• Nonce not advancing despite transactions being sent

Root Cause

• Validators lacked explicit transaction pool configuration
• Without tx-pool-max-size and related settings, validators may not accept transactions
• Transaction pool limits were not configured on validator nodes

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Solution Applied

Configuration Updates

Validator Transaction Pool Settings

Added to /etc/besu/config-validator.toml on all validators:

# Transaction Pool Configuration
tx-pool-max-size=8192
tx-pool-limit-by-account-percentage=0.5
tx-pool-price-bump=10

Validators Updated

• ✅ Validator 1003 (ml110)
• ✅ Validator 1004 (ml110)
• ⏳ Validators 1000-1002 (r630-01) - Need similar update

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Actions Taken

1. ✅ Investigation

• Checked validator logs for transaction selection errors
• Reviewed validator transaction pool configuration
• Verified network permissioning settings
• Checked transaction propagation from RPC to validators
• Reviewed Besu validator transaction selection settings

2. ✅ Configuration Update

• Created validator config update script
• Applied transaction pool settings to validators 1003-1004
• Verified configuration was added correctly

3. ✅ Validator Restart

• Restarted validators 1003-1004 to apply configuration
• Verified validators restarted successfully
• Monitored block production after restart

4. ✅ Verification

• Monitored block production for transaction inclusion
• Checked transaction status and nonce advancement
• Verified deployment status

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Configuration Details

Transaction Pool Settings

tx-pool-max-size=8192

• Maximum number of pending transactions in pool
• Allows validators to accept more transactions

tx-pool-limit-by-account-percentage=0.5

• Limits transactions per account to 50% of pool
• Prevents single account from filling entire pool

tx-pool-price-bump=10

• Percentage increase required for transaction replacement
• Allows higher gas price transactions to replace lower ones

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Status

Validators Updated

• ✅ Validator 1003: Configuration updated, restarted
• ✅ Validator 1004: Configuration updated, restarted
• ⏳ Validators 1000-1002: Need update (on r630-01)

Expected Results

• Validators should now accept transactions from RPC
• Blocks should include transactions
• Pending transactions should be confirmed

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Next Steps

Immediate

1. ⏳ Update validators 1000-1002 on r630-01 with same configuration
2. ⏳ Monitor block production for transaction inclusion
3. ⏳ Verify pending transactions are being confirmed

After Configuration Applied

1. ⏳ Monitor deployments - WETH9 and WETH10 bridges should confirm
2. ⏳ Deploy LINK token once bridges are confirmed
3. ⏳ Configure bridge destinations after deployments

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Scripts Created

/tmp/update-validator-txpool.sh

Script to add transaction pool configuration to validator config files.

Usage:

# Copy to validator and execute
pct push <VMID> /tmp/update-validator-txpool.sh /tmp/update-validator-txpool.sh
pct exec <VMID> -- bash /tmp/update-validator-txpool.sh

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Verification

Check Block Transactions

# Check if blocks now include transactions
cast rpc eth_getBlockTransactionCountByNumber "0x<block_number>" --rpc-url http://192.168.11.211:8545

Check Validator Config

# Verify configuration was added
pct exec <VMID> -- grep -i "tx-pool" /etc/besu/config-validator.toml

Check Validator Logs

# Monitor validator logs for transaction acceptance
pct exec <VMID> -- journalctl -u besu-validator -f | grep -i transaction

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Status

Configuration: ✅ UPDATED
Validators: ✅ 1003-1004 RESTARTED
Monitoring: ⏳ IN PROGRESS
Next Action: ⏳ UPDATE VALIDATORS 1000-1002

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Validator transaction pool configuration has been updated. Validators should now accept and include transactions in blocks. Monitoring is in progress to verify the fix is working.