> ## Documentation Index
> Fetch the complete documentation index at: https://optimism-373f39ad-sdm-docs-revisit.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Legacy Geth configuration

> Learn how to configure Legacy Geth for serving historical execution traces on upgraded OP Stack networks.

Legacy Geth (`l2geth`) is the old pre-Bedrock OVM client running against a preconfigured data directory.
It is required only for upgraded networks like OP Mainnet to serve execution traces and chain data from before the Bedrock upgrade.
If you're running a node that had a chain genesis after the Bedrock upgrade, you do not need Legacy Geth.

<Info>
  Legacy Geth (`l2geth`) is the pre-Bedrock OVM client and is unrelated to op-geth's deprecation. l2geth is required on OP Mainnet archive nodes regardless of which post-Bedrock execution client you run (op-reth or op-geth).
</Info>

<Info>
  If you need state proofs for post-Bedrock blocks (for example, for withdrawal proving), see the [historical proofs config](/node-operators/reference/op-reth-historical-proof-config) — that's a different feature.
</Info>

## Do you need Legacy Geth?

op-reth routes RPC requests that target pre-Bedrock blocks to Legacy Geth.
This includes *historical execution* — methods that need to execute pre-Bedrock transactions, such as `eth_call` and the `debug_trace*` methods — as well as reads of pre-Bedrock block and transaction data, such as `eth_getBlockByNumber` and `eth_getTransactionReceipt`.
op-reth serves everything post-Bedrock directly.
If you do not need any RPC access to pre-Bedrock blocks, then you do not need to run Legacy Geth at all.

For the exact list of RPC methods routed to Legacy Geth, see the [Legacy Geth configuration reference](/node-operators/reference/legacy-geth-config#rpc-methods-routed-to-legacy-geth).

## Setup

### 1. Download the preconfigured data directory

Download and extract the Legacy Geth data directory, which is available at [datadirs.optimism.io](https://datadirs.optimism.io).

```bash theme={null}
# Download the data directory
curl -o legacy-geth-datadir.tar -sL <URL-to-legacy-datadir>

# Extract it
tar -xvf legacy-geth-datadir.tar -C /data/legacy-geth
```

### 2. Configure Legacy Geth

Run Legacy Geth with the minimum required configuration:

```bash theme={null}
USING_OVM=true \
  ETH1_SYNC_SERVICE_ENABLE=false \
  RPC_API=eth,rollup,net,web3,debug \
  RPC_ADDR=0.0.0.0 \
  RPC_CORS_DOMAIN=* \
  RPC_ENABLE=true \
  RPC_PORT=8545 \
  RPC_VHOSTS=* \
  geth --datadir /data/legacy-geth
```

<Warning>
  It is imperative that you specify the `USING_OVM=true` environment variable.
  Failing to specify this will cause `l2geth` to return invalid execution traces or panic at startup.
</Warning>

The full set of environment variables Legacy Geth accepts, with defaults, is catalogued in the [Legacy Geth configuration reference](/node-operators/reference/legacy-geth-config#environment-variables).

### 3. Configure your execution client to route to Legacy Geth

Point your execution client at Legacy Geth with the `--rollup.historicalrpc` flag; op-reth and op-geth accept the same flag (see the [routing-flag reference](/node-operators/reference/legacy-geth-config#execution-client-routing-flag)).

<Tabs>
  <Tab title="op-reth">
    ```bash theme={null}
    op-reth node \
      --datadir=/data/optimism \
      --rollup.historicalrpc=http://localhost:8545 \
      # ... other flags
    ```
  </Tab>

  <Tab title="op-geth">
    <Warning>
      **op-geth has reached end-of-support (2026-05-31) and does not support the now-active Karst hardfork, so op-geth nodes can no longer follow the canonical chain.** Migrate to op-reth, the primary supported execution client. See the [op-geth deprecation notice](/notices/archive/op-geth-deprecation) for the full migration plan.
    </Warning>

    ```bash theme={null}
    geth \
      --datadir=/data/optimism \
      --rollup.historicalrpc=http://localhost:8545 \
      # ... other flags
    ```
  </Tab>
</Tabs>

## Troubleshooting

<Warning>
  `l2geth` is based on an old version of geth where trace functionality is unstable.
  It is no longer maintained and will not be updated.
</Warning>

### Legacy Geth won't start

**Problem**: `l2geth` panics or returns errors on startup

**Solution**: Ensure `USING_OVM=true` is set in your environment variables

### Invalid execution traces

**Problem**: Legacy Geth returns invalid or incorrect trace data

**Solution**: Verify that `USING_OVM=true` is set and the data directory is complete and uncorrupted

### Execution client not routing to Legacy Geth

**Problem**: Historical execution requests are not being routed to Legacy Geth

**Solution**: Check that `--rollup.historicalrpc` is set on your execution client (op-reth or op-geth) with the correct URL to Legacy Geth