Rachio3 - Rachio detected a fault in zone master valve

Every time Rachio turns on, it throws the following error " Rachio detected a fault in zone master valve while running a schedule on your Rachio controller" & “As a result, master valve will continue to run as scheduled, but no water will flow to the zone.”

It says that water wont flow in the error email, but I see water being sprayed out during the cycle. And the same error message is thrown for all 8 zones that I have.

I have rain sensor installed, so tried disconnecting points ‘S1’ & ‘S2’, but that did not resolve the issue.
Than I tried disconnecting the wire which I think is master valve connect to point ‘M’ on the board, that seemed to have stopped the error messages.

My a newbie and I have no idea what I am doing, and was not sure if disconnecting the ‘M’ wire is good or not. Any suggestions are appreciated!