Invalid request errors with skipCache in JSON-RPC request

[KaiRo-at]

• OpenEthereum version: 3.0.1
• Operating system: Linux
• Installation: docker
• Fully synchronized: yes
• Network: ropsten
• Restarted: yes

This was first reported and worked around in https://github.com/MetaMask/web3-provider-engine/issues/311 but it may actually be an OpenEthereum issue.

Quoting from the web3-provide-engine issue:

Web3 is polling the blockNumber with the request:

{"id":1,"jsonrpc":"2.0","params":[],"method":"eth_blockNumber","skipCache":true}

The parity (v2.4.5) node is responding with

{"jsonrpc":"2.0","error":{"code":-32600,"message":"Invalid request"},"id":1}

I'm seeing the same issue with OpenEthereum 3.0.1 from docker when trying to deploy contracts via truffle, see some of my output in https://github.com/trufflesuite/truffle/issues/3182#issuecomment-660989269

It may be that skipCache is a non-standard option that correctly isn't supported in OpenEthereum, or it may be a bug, I'm not sure, but I wanted to let the OE team know. ;-)

[adria0]

@KaiRo-at, I do not see any skipCache entry in the OpenEthereum source code, so it seems that this is something specific of other implementations