There seems to be an issue with latest update. The url of the pool is not correctly passed to the miner, it's blank. Please fix it asap.
Since 5.1.
Press M, to remove old incompatible miners.
And check actual existing pools:
https://github.com/Quake4/MindMiner/tree/master/PoolsPlease, remove old pools.
Tried it and same thing. You have to replace everything in order to make it work.