> ## Documentation Index
> Fetch the complete documentation index at: https://docs.berachain.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Osaka1 Upgrade

> Validator and developer changes from the Osaka1 upgrade on Berachain Bepolia.

Osaka1 is a Berachain-specific execution-layer hardfork that floors the **minimum base fee** and **minimum blob base fee** at **1 gwei** each after activation.

## Upgrade timing

| Network         | Activation Date (UTC)       | Binaries Available |
| --------------- | --------------------------- | ------------------ |
| Bepolia Testnet | 4pm July 22, 2026           | July 14            |
| Mainnet         | Placeholder activation time | —                  |

## What changes

After the fork activates, Bera-Reth enforces configurable floors on the two EIP-1559 fee parameters:

* **Minimum base fee:** `1 gwei` (`1_000_000_000` wei). The next-block base fee can no longer decay below this value.
* **Minimum blob base fee:** `1 gwei` (`1_000_000_000` wei). The EIP-4844 blob base fee is lifted to this floor, shifting the entire exponential curve baseline.

## Configuration

Osaka1 is carried in the built-in `--chain bepolia` preset shipped with Bera-Reth v1.4.3-rc.0. The Berachain genesis `berachain.osaka1` block for Bepolia is:

```json theme={null}
"osaka1": {
  "time": 1784736000,
  "minimumBaseFeeWei": 1000000000,
  "minimumBlobBaseFeeWei": 1000000000
}
```

`1784736000` is `2026-07-22 16:00:00 UTC`. The matching chainspec is [available in the Beacon Kit v1.4.2-rc.0 genesis file](https://raw.githubusercontent.com/berachain/beacon-kit/v1.4.2-rc.0/testing/networks/80069/eth-genesis.json).

## Upgrade instructions

1. Download the [recommended versions](/nodes/architecture/evm-execution) for Bepolia:
   * **Bera-Reth v1.4.3-rc.0**
   * **Beacon-Kit v1.4.2-rc.0**
2. If you use the built-in chain preset, keep your Bera-Reth startup as `--chain bepolia`. The preset carries Osaka1 automatically; no genesis file change is needed.
3. If you use `--chain <path>`, fetch the [Bepolia genesis from Beacon Kit v1.4.2-rc.0](https://raw.githubusercontent.com/berachain/beacon-kit/v1.4.2-rc.0/testing/networks/80069/eth-genesis.json) and overwrite your current genesis file. Verify the md5: `f7d31d1039b0253f5f43336e55d28054`.
4. No changes are needed to BeaconKit options.
5. Start the new `beacond` and `bera-reth` binaries.