I am getting this error as well, but it is happening when I create a job in Workflow Manger 10.1. I am working with SQLServer 2008 R2. The configuration .jxl I imported when setting up this new WMX instance was from a Workflow Manager 10.0 instance. I suspect that might have something to do with it, but I have not been able to find anything that says this should/can be a problem. Everything I have seen online says importing .jxls from previous versions is supported.