Issues with Proposal on Moonriver

:computer: Environment
When creating a proposal for a contract on Moonriver, an error occurs.

Error: Transaction validation failed. This usually means that this proposal would fail to execute given its current parameters. Make sure all involved accounts have the necessary permissions for the transaction to succeed.

:memo:Details

Moonriver changed their RPC to https://rpc.api.moonriver.moonbeam.network/

:1234: Code to reproduce