Balance becomes zero after changing Account address type from Substrate address to Ethereum address

Question

I am working on a scenario, where I have to upgrade my application and change account address type(from Substrate address to Ethereum address[similar to moonbeam unified account]).

I made the corresponding changes. There is code version A which supports Substrate address and code version B supports Ethereum address.

If I run code version B, it works fine. I am able to see balances of genesis accounts.

If I run code Version A and perform runtime upgrade for version B, balances of genesis accounts become zero after runtime upgrade.

Unfortunately I won't be able to share code but any help/thought would be appreciable.

Can someone please give me an idea what was happening inside?

Answer 1

That's true.

You shouldn't see any balances.

Here is how the account data is stored:

Account StorageMap - 32 bytes -> account data

After the runtime upgrade it was changed to:

Account StorageMap - 20 bytes -> account data

But you didn't do any migration for the DB.

The old data is still a 32 -> data map in the DB.

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Check how I do the migration:

https://github.com/darwinia-network/darwinia-2.0/blob/92533724d8192f8917b51f0eaf5dc665bfe3317e/pallet/account-migration/src/lib.rs#L19-L41