# Overview

This section documents each MegaETH network upgrade, describing what changed, why, and what developers need to know.

## Hardfork History

### [MiniRex](/spec/network-upgrades/minirex.md)

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{% tab title="Testnet" %}
`0` (Genesis)
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`0` (Genesis)
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[Dual gas model](/spec/megaevm/dual-gas-model.md), [multidimensional resource limits](/spec/megaevm/resource-limits.md), [gas detention](/spec/megaevm/gas-detention.md), 98/100 gas forwarding, SELFDESTRUCT disabled, system contracts ([Oracle](/spec/system-contracts/oracle.md), [Timestamp](/spec/system-contracts/high-precision-timestamp.md))

### MiniRex1

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N/A
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`1764845637` (Dec 4, 2025, 10:53 UTC)
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Rollback: reverted to Equivalence spec (maps to `EQUIVALENCE`). The MiniRex features were deactivated on the network; no chain reorg or state rollback occurred. Contracts deployed during MiniRex remained on-chain.

### MiniRex2

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N/A
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`1764849932` (Dec 4, 2025, 12:05 UTC)
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Restoration: re-activated MiniRex spec (maps to `MINI_REX`). All MiniRex features (dual gas model, resource limits, gas detention) were re-enabled.

### [Rex](/spec/network-upgrades/rex.md)

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{% tab title="Testnet" %}
`1764694618` (Dec 2, 2025, 16:56 UTC)
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{% tab title="Mainnet" %}
`1764851940` (Dec 4, 2025, 12:39 UTC)
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{% endtabs %}

Transaction intrinsic [storage gas](/spec/reference/glossary.md#storage-gas), revised storage gas economics (`base × (multiplier − 1)`), consistent CALL-like opcode behavior, [state growth](/spec/megaevm/resource-accounting.md#state-growth) tracking

### [Rex1](/spec/network-upgrades/rex1.md)

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{% tab title="Testnet" %}
`1766147599` (Dec 19, 2025, 12:33 UTC)
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{% tab title="Mainnet" %}
`1766282400` (Dec 21, 2025, 02:00 UTC)
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Fix: [compute gas](/spec/reference/glossary.md#compute-gas) limit reset between transactions

### [Rex2](/spec/network-upgrades/rex2.md)

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{% tab title="Testnet" %}
`1770116400` (Feb 3, 2026, 11:00 UTC)
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{% tab title="Mainnet" %}
`1770246000` (Feb 4, 2026, 23:00 UTC)
{% endtab %}
{% endtabs %}

SELFDESTRUCT re-enabled ([EIP-6780](https://eips.ethereum.org/EIPS/eip-6780)), [KeylessDeploy](/spec/system-contracts/keyless-deploy.md) system contract

### [Rex3](/spec/network-upgrades/rex3.md)

{% tabs %}
{% tab title="Testnet" %}
`1771380000` (Feb 18, 2026, 02:00 UTC)
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{% tab title="Mainnet" %}
`1771639200` (Feb 21, 2026, 02:00 UTC)
{% endtab %}
{% endtabs %}

[Oracle](/spec/system-contracts/oracle.md) gas cap raised to 20M, SLOAD-based oracle detention, keyless deploy compute gas tracking

### [Rex4](/spec/network-upgrades/rex4.md)

Per-[call-frame](/spec/reference/glossary.md#call-frame) resource budgets, relative gas detention, [storage gas stipend](/spec/reference/glossary.md#storage-gas-stipend), MegaAccessControl, MegaLimitControl, sandbox environment inheritance.

### [Rex5](/spec/network-upgrades/rex5.md) *(unstable)*

[SequencerRegistry](/spec/system-contracts/sequencer-registry.md) system contract, [Oracle](/spec/system-contracts/oracle.md) v2.0.0 with dynamic system address, caller-account update deduplication for [data size](/spec/megaevm/resource-accounting.md#data-size) and [KV updates](/spec/megaevm/resource-accounting.md#kv-updates), [KeylessDeploy](/spec/system-contracts/keyless-deploy.md) trailing-bytes rejection.

## How to Read These Pages

Each upgrade page follows a consistent structure:

* **Summary** — What changed and why
* **What Changed** — Previous vs new behavior for each change
* **Developer Impact** — What contract authors and integrators need to know
* **Safety and Compatibility** — Backward-compatibility boundaries and failure-mode differences
* **References** — Links to the normative spec and related documentation


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