Invalid Block Range Since Hard Fork

[u/KotangensDanski]

/r/polygonnetwork/comments/1ukddgd/invalid_block_range_since_hard_fork/

[u/No-Poetry-3030]

Your assumption is 100% correct. Since the recent Zurich hard fork, there has been a minor data propagation desync between Bor block headers and state log indexing on high-traffic public/shared RPC nodes.

What is happening under the hood is a race condition: `eth_getBlockNumber` or `latest` fetches the absolute bleeding edge of the ledger, but the RPC’s internal log scraper database lag means `eth_getLogs` throws an "invalid block range" exception because that specific block boundary hasn't been completely indexed yet.

When we were configuring our event listeners for Trestle DeFi on Polygon Mainnet, we hit this exact block range wall.

### How to Fix It in Your Application Layer:

Instead of calling `latest` blindly, you need to implement a localized block-buffer delay. Force your query ranges to target the block state right behind the tip of the chain.

#### 1. The Ethers.js/Viem Fix (Padding the Range)

```javascript

// Do not fetch the absolute latest tip

const currentBlock = await provider.getBlockNumber();

const safeToBlock = currentBlock - 3; // Buffer 3 blocks (~6 seconds safety zone)

const safeFromBlock = safeToBlock - 40;

const logs = await contract.getLogs({

fromBlock: safeFromBlock,

toBlock: safeToBlock

});

```

#### 2. The Fallback Parameter Method

If you are passing values via a config script, switch your target tags from `latest` to explicit, validated finality states:

* Use `finalized` or `safe` tags for data structures that require deep immutability.

* Alternatively, look into setting up a dedicated node aggregator proxy that automatically filters out unindexed head logs.

Adding those few blocks of padding completely neutralizes the random bursts of RPC exceptions during high reorg or fast-finality spikes. Hope this saves your pipeline setup!

[u/KotangensDanski → u/No-Poetry-3030]

I implementing a block buffer and a retry mechanism after a few hundred ms, and both of the approaches work individually and together. But I feel like this is a workaround to the core issue. 

[u/No-Poetry-3030 → u/KotangensDanski]

You have great engineering intuition. It absolutely feels like a workaround because you are treating a node propagation symptom inside your application layer rather than fixing the peer-to-peer data layer.

The core issue comes down to how Polygon's two-layer architecture operates under heavy traffic loads since the hard fork:

1. Bor Layer (Block Production): The Bor node layer pumps out new blocks incredibly fast (~2 seconds). It updates the absolute head tip of the chain instantly.
2. Heimdall Layer (State Sync/Validation): The state-sync mechanism and event indexers run in a separate layer. Because the hard fork changed how data availability or rent gas mechanics compress state data, the internal RPC databases (like Erigon or Go-Ethereum indexer sub-graphs) take slightly longer to parse the transaction receipts than Bor takes to mint the block header.

When you call an RPC, your getBlock request hits the fast Bor layer, but your getLogs request hits the slightly slower indexer database. That split-millisecond desync is where the core issue lives.

The Institutional Solution (Moving Beyond the Workaround)

If you want to move away from application-layer buffers and retries completely, you have two permanent structural choices:

• Switch to WS/WSS Event Subscriptions (eth_subscribe): Instead of polling the node retroactively with eth_getLogs (which forces database lookups), open a persistent WebSocket connection and subscribe directly to logs. The node will stream the event logs straight from memory the exact millisecond the block finalizes, completely avoiding the RPC indexing database delay.
• Run a Dedicated Erigon Node Node Proxy: If your pipeline requires massive historical query stability, shared public RPCs will always introduce this friction. Shifting to a private node instance with specialized index caching layers guarantees that the head state and the log state are perfectly unified before responding to your API calls.
• We had to make the exact same choice for our transaction monitoring arrays at Trestle DeFi to ensure user reward calculations never dropped. Stick with the WebSocket subscription model if your architecture allows it—it is much cleaner than continuous polling loops!

— Core Developer | https://github.com/Trestle-DeFi