See attached image illustrating how to view the CBECC log file. In my experience, the CBECC log file isn’t the most helpful with troubleshooting errors.
Based on your error, it sounds like you have modeled overhangs or sidefins. Doing this requires you to input the location of window and door elements within each wall. The error indicates that one or more of your window/door elements have been specified in the same location on the wall, i.e. they “overlap”.
I would recommend clicking through each of your wall elements in which there is a door or a window and verify the wall widths and wall heights are accurate. I would then click through the windows and doors in each wall and verify the widths, heights, and X and Y position on wall are accurate. If you do this, you will likely find that one or more of the window/door elements are overlapping on your walls.
I have found it helpful to do a little sketch drawing for each wall, in which the wall is drawn based on the width and height input into the model and then the windows and doors are drawn onto the wall based on the specified width, height and X and Y position or each window and door in the model.
Also, I have been told that modeling sidefins and overhangs is optional. We typically avoid doing it because it complicates the model so much. We will only model them if needed for compliance. I have rarely needed to include them to get a model to comply.
Also note that in heating climates, sidefins and overhangs typically hurt you on compliance.