You want to switch your wallet from one delegation contract to another. The new contract address is safe, and the code is public. You think it is fine. You sign the new delegation and submit it on-chain.
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Then the data in your wallet gets messed up. The balance shows incorrectly, transfers fail, or even the whole account becomes locked.
This is not because the new contract is broken. It is because the storage data left by the old contract does not match the data format the new contract expects.
First Look at the Wrong Result: Account Locked or Abnormal Data
After you re-delegate, your account may have these problems:
Transactions fail with messages like "invalid storage slot" or "unexpected state"
The balance shown in your wallet does not match the on-chain balance
Some features suddenly stop working
The account becomes completely unusable and you need to contact support to recover it
This is the result of a "storage collision."
Reconstructing the Wrong Path: Why Storage Collisions Happen
EIP-7702 allows EOA accounts to execute smart contract code through delegation. But there is a key design point: when you switch delegation, the storage data written by the old contract is not automatically cleared.
When a user switches delegation contracts, the storage data written by the old contract remains in the EOA's storage. If the old and new contracts use the same storage slot to represent different types of data, the new contract will incorrectly read the leftover data from the old contract, causing logic to break.
For example:
Contract A uses slot 0 to store the user's "nonce"
Contract B uses slot 0 to store the user's "owner address"
You switch from A to B. B reads slot 0 and treats A's nonce value as the owner address
The result is: the account configuration is wrong, or the account becomes completely unusable.
SlowMist clearly pointed out in a security warning after the Pectra upgrade that developers should follow the namespace formula proposed by ERC-7201 to reduce storage collisions. If developers do not isolate storage properly, users will step on this trap when switching delegation contracts.
Comparison of Correct and Incorrect Approaches
| Approach | Explanation |
|---|---|
| Incorrect approach | Directly re-delegate without checking whether the old and new contracts have different storage layouts. |
| Correct approach | Before migrating, confirm whether both the old and new delegation contracts implement namespace storage (ERC-7201). Or first clear the old delegation by pointing it to the zero address, then delegate to the new contract, making sure old storage data is cleaned up. |
Follow This Process Before Migrating to a New Delegation Contract
Goal: Avoid account abnormalities caused by storage collisions.
Steps, in order:
Step 1: Confirm the storage layout of the old and new contracts
Check the code of the old and new contracts on Etherscan or a block explorer. Confirm whether both contracts follow the ERC-7201 namespace storage pattern.
How to tell: Search the contract code for ERC-7201 or NAMESPACE-related markers. If the old contract uses the default "continuous storage slots" pattern in Solidity, and the new contract also uses the default pattern, a collision is very likely. If both use namespace isolation, the risk is lower.
Completion standard: You can confirm whether the storage management methods of the old and new contracts are compatible. If you are not sure, choose the second safer operation method.
Step 2: If you cannot confirm storage compatibility, clear first and then delegate
The safest method has two steps:
First send a 0x04 transaction pointing to the zero address to clear the old delegation and restore the account to a normal EOA.
After confirming the clearing is successful, send a new 0x04 transaction pointing to the new contract address.
Completion standard: Only initiate the new delegation after you confirm that the "Authorizations (EIP-7702)" field on Etherscan is empty or shows the zero address. Leave at least one block interval between the two steps.
Step 3: Check whether the delegation contract implements the necessary callback functions
After migration, if NFT transfers or other ERC-721/ERC-1155 operations fail, it may be because the delegation contract lacks the onERC721Received or onERC1155Received callback functions. Before migrating, check the contract documentation to confirm that it implements the receiving functions required by mainstream token standards.
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Checklist for Broader Troubleshooting
| Check item | Safe status | Danger signal |
|---|---|---|
| Old and new contract storage layout | Both use ERC-7201 namespace isolation | Use default continuous storage slots |
| Migration process | Clear old delegation first, then delegate to new contract | Directly overwrite delegation |
| Whether the contract implements callbacks | Has implemented onERC721Received and other functions | Missing necessary receiving functions |
| Old storage data cleanup | Call the old contract's cleanup interface | Old data is not cleaned up |
Risk reminder: When re-delegating under EIP-7702, the old contract's storage data is not automatically cleared. If the storage layouts of the old and new contracts are incompatible, the account may be locked and funds may be stuck. Before re-delegating, first confirm whether the new contract is designed to be storage-compatible with the old contract, or reset the delegation by pointing it to the zero address before delegating.
