# Overtime Account Migration
## Overview
Overtime is upgrading user smart accounts from Biconomy V2 to Biconomy Nexus Accounts with Modular Execution Environment.
This upgrade is required to keep user accounts compatible with the latest account abstraction infrastructure and future roadmap, improve reliability, and unlock potential new features. To complete the upgrade, users must click the UPGRADE button in the Overtime frontend and execute the onchain signature.
This is a one-time, user-triggered migration. No funds are at risk and ownership of the account remains fully with the user with the same individual Overtime Account address.
### What Is Being Upgraded?
Overtime Accounts on the Overtime dapp are smart contract wallets (also called smart accounts) that simplify user experience from regular EOAs, while maintaining full non-custodial and onchain nature of the product.
Historically, these accounts were deployed using Biconomy V2 Smart Accounts. The platform is now migrating to Biconomy Nexus Accounts, which are built on MEE.
**In short:**
| **Before** | **After** |
| --------------------------- | ----------------------------------- |
| Biconomy V2 Smart Account | Biconomy Nexus Smart Account |
| Legacy account architecture | Modular, future-proof architecture |
| Limited extensibility | Native support for advanced modules |
### Why This Upgrade Is Necessary
#### 1. End of Lifecycle for Biconomy V2
Biconomy V2 Smart Accounts are part of an older generation of account abstraction infrastructure. While still functional, they are no longer the recommended standard and will not receive the same level of feature support moving forward.
Upgrading ensures long-term compatibility and avoids technical debt.
#### 2. Nexus Accounts Are the New Standard
Biconomy Nexus introduces a modular smart account architecture. This design allows:
* Safer upgrades in the future
* Cleaner separation of logic (validation, execution, permissions)
* Better compatibility with evolving ERC-4337 tooling
For users, this means a more robust and maintainable account, even if the day-to-day UX stays the same.
#### 3. Required for Upcoming Features & Fixes
Some upcoming improvements on Overtime Markets depend on Nexus-specific functionality, including:
* Improved transaction handling
* More reliable gas abstraction and relaying
* Safer extensibility for future account features
Without upgrading, older smart accounts may become partially incompatible with new releases.
***
## Wha**t** Happens When You Click `UPGRADE`
When a user clicks **`UPGRADE`**, the frontend initiates a *single atomic onchain transaction* that performs the smart account migration from **Biconomy V2 Smart Account** to a **Biconomy Nexus smart account built on the Modular Execution Environment (MEE)**.
{% hint style="info" %}
The Overtime Account upgrade is **network-specific**. If the Overtime Account is upgraded on one network, the upgrade will **not** carry over to other networks. To use the Overtime Account on a different network, the user must execute the **`UPGRADE`** process again on that network.
{% endhint %}
Here’s exactly what the upgrade process does:
1️⃣ Prepares an Onchain Upgrade Operation
* The upgrade constructs **low-level calldata** that encodes two actions:\
• Update the smart account’s implementation logic to the Nexus version\
• Initialize the Nexus account environment for this user
* Both of these actions are bundled into a single batched execution so they run **atomically** in one state transition. If one part fails, nothing is applied.
2️⃣ Upgrade the Smart Account Implementation (Onchain Logic)
* The smart contract wallet’s internal implementation pointer is updated in-place to the new **Nexus/MEE implementation** — this does *not* change the account’s address or storage.
* This step preserves:\
• The existing account address\
• All funds and assets\
• All relationships with other contracts
* The implementation update is performed via an encoded function call to `updateImplementation`.
3️⃣ Initialize the Nexus Environment
* After the implementation pointer is updated, the account must be *initialized as a Nexus account*.
* This involves setting up the **modular execution environment (MEE)** and a default validator so the account can operate under Nexus rules and standards.
* A separate encoded function call to `initializeAccount` is prepared with all necessary initialization data.
4️⃣ Batch Execution — Single Atomic Action
* Both the **implementation upgrade** and **Nexus initialization** calls are combined via a `executeBatch` call inside the smart account.
* This ensures **no partial upgrade state** can occur — either the whole migration executes, or it doesn’t.
5️⃣ Wrap It in an ERC-4337 UserOperation
* To make this upgrade usable in an account abstraction flow:\
• A standard ERC-4337 `UserOperation` is built\
• The upgrade calldata becomes the transaction payload\
• The operation is signed by the existing account owner using normal account signing logic
* This allows the upgrade to be processed through the EntryPoint as a normal user operation, even after Biconomy’s bundled service shuts down.
6️⃣ POST DISCONTINUATION: Submit Through a Mini Bundler or EntryPoint
* Because Biconomy’s hosted bundler service is being discontinued, the EOA wallets can act as a **mini bundler**:\
• It packages the user operation\
• Submits it directly to the ERC-4337 EntryPoint contract\
• Handles gas and transaction submission without reliance on external bundlers
* The result is the same as a regular transaction: it gets mined, confirmed, and the account is migrated.
**🧠 What the Upgrade *****Doesn’t***** Do**
✔ It does **not transfer funds**\
✔ It does **not change account ownership**\
✔ It does **not generate a new wallet key or new address**\
✔ It does **not require manual asset movement**
All balances, ownership, and external contract relationships remain intact. The only change is the **underlying account logic and execution environment**.
**🎯 End Result**
Once the upgrade transaction is confirmed:
* Your smart account now runs on **Biconomy Nexus with MEE support**
* The same account address continues to be used
* The account is ready for future features, modules, and upgrades supported by Nexus and MEE
* You can continue using the dapp exactly as before now on an improved account backbone.
{% hint style="warning" %}
## **Is This Upgrade Mandatory?**
**Yes.**
Users must upgrade to continue using Overtime without interruptions. Biconomy V2 accounts lose compatibility with new transactions flow or features.
{% endhint %}
***
## Biconomy Nexus Advantages
#### [](https://docs.biconomy.io/new/learn-about-biconomy/nexus#performance-&-cost-efficiency)Performance & Cost Efficiency
**25% lower gas costs** compared to alternative implementations through optimized contract design
* **Batched operations** via ERC-7579 modules reduce transaction overhead
* **Efficient calldata encoding** minimizes L2 data availability costs
#### [](https://docs.biconomy.io/new/learn-about-biconomy/nexus#composable-batching)Composable Batching
Nexus is the only smart account solution on the market enabling composable batch execution. It allows developers to encode batch calls where the next instruction depends on the output of the previous one.
* **EIP-7702 compatibility** ensures forward compatibility with Ethereum’s account abstraction roadmap
* **Modular design** (ERC-7579) enables you to install third-party modules on user accounts
* **Cross-chain support** includes all major EVM networks with unified deployment addresses
For developers
* **AbstractJS SDK** provides type-safe interfaces for account interactions
* **Pre-built modules** for common features (recovery, spending limits, session keys)
* **Standardized interfaces** ensure compatibility with ecosystem tooling
* **Comprehensive documentation** with implementation examples and best practices
Security
* **92% DefiSafety score** demonstrates adherence to security best practices
* **Battle-tested contracts** with 2M+ smart accounts, $500M+ value processed without incidents
* [Contracts and Audits of Biconomy MEE Contracts Suite](https://docs.biconomy.io/contracts-and-audits)
***
## Summary
* Overtime is upgrading smart accounts from Biconomy V2 to Biconomy Nexus (MEE)
* This ensures long-term compatibility, security, and feature support
* Users must execute **`UPGRADE`** once to migrate their account
* Funds, ownership, and access remain unchanged
{% hint style="warning" %}
If you see the **`UPGRADE`** prompt, please complete it to continue using the dapp seamlessly.
{% endhint %}
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