Mining Issue on Ethereum family
### Description
I was never able to setup the mining rig to mine any ethereum family coins on miningcore. The stratum closes the connection immediately after the connection accepted. Is this a known issue to miningcore? I'm asking because I even had the same problem when I wanted to mine ETC on https://coinfoundry.org/ and when I told @oliverw he removed ETC from the pool.

[Description of the issue]
Here is the log for the miningcore:
![image](https://user-images.githubusercontent.com/22977536/51434103-85219000-1cad-11e9-973f-6337e80c29a5.png)

Here is the log for mining rig:
![image](https://user-images.githubusercontent.com/22977536/51434051-599ea580-1cad-11e9-9eaa-a3b8fb3b8e71.png)

### Expected behavior
Start mining Without issue.

### Actual behavior
Closing the connection immediately.

### Reproduces how often

100%

### Version
Latest version

### Additional Information

I tried to debug this by pointing the mining rig to my local and here is the error I'm getting:
![image](https://user-images.githubusercontent.com/22977536/51434173-b77fbd00-1cae-11e9-8a23-1254fd734be2.png)
I tried this on the following chains using parity: Classic Kovan Mainnet Testnet and the result was always the same, Is this normal?