This error most likely caused by either the inability of the nodes to access the shared server files, or a failure to properly update the WSS connector during the maintenance update.
1.Please confirm that the nodes are able to access the shared server file.
2.If the nodes are accessible then delete the WSS folder from <Atom Home>/Connector directory and <Atom Home>/Work directory.
3. Stop the molecule, and then start it. This should force the reload of the WSS connector.