A extension module for UE4 ControlRig
Navigate to the ControlRigExt Content folder and open up EUW_ControlRigTools
Right click on it, and hit Run Editor Utility Widget
Once you have done that, you can now run your Editor Utility Widget in Window->Editor Utility Widget
If you ever seen this issue when running the tool
Navigate to the ControlRigExt Content folder and open up EUW_ControlRigTools
You should see the error nodes in the Editor Utility Widget
Select any red node, right click and hit "Refresh Nodes"
Afterwards, you will then go to File->Refresh All Nodes and Save
You will also need to do it for the EUW_ControlRigRenameTool