I know this is old, but I have seen multiple people mention this same issue across multiple threads and chat servers but none of the recommendations worked for me, so I'm sharing here. Tangent - I found it odd that the parent error so often seemed to occur with objects that had "Circle" in the name... and in my case too, which is what spurred the in-depth review. This may not work for everyone, but I wanted to share the troubleshooting process and what worked for me. Note: I use FS viewer, so some features may differ.
TL;DR: Remove spaces and special characters from your object / mesh ID data names (the level with the little green triangle) and try to upload again.
Error: LOD Model has no parent
- In the viewer, look at the Log tab on the model uploader and enable "Show detailed logging"
- At the bottom of the log area, click "Clear settings/reset form" and wait for the log to update again
- Scroll down the list until you see object(s) throwing error(s)
- Examples:
- "LOD4: List of models does not include Circle"
- "Model Circle was not used - mismatching lod models."
- "Model Circle_LOD0 was not used - mismatching lod models."
I had nothing in my file specifically named "Circle", so I had to figure out a way to identify which object it was referring to...
- Open the .dae file with Xcode (or Windows equivalent) and click the little panel icon at the bottom to open Scene Graph View on the left nav to list all components
- Find the corresponding object(s) in the list with a matching name (if there is a way to view this in Blender, that info would be appreciated, as it did not match anything I had visibility to by default...)
- Click the object(s) in the left nav to see it highlight in the preview - that is your potential culprit
- If you have multiple items with the same object name, they may not be in the order you expect on the left. Scroll through the list, selecting and making a note of which objects you need to check as you go
- Go back to Blender, select each potential culprit object in the viewport individually to review
- In the outliner Scene (defaulted on the right nav), expand to look at the corresponding object (orange triangles) / mesh ID data names (little green triangles)
- Edit the data related to object(s) / mesh - rename, ungroup, etc to test
- Go back to SL, try the upload again (be patient while it processes, as it can take a moment)
- Recheck the log for more errors, if necessary, and work from there
In my instance, I had 16 objects named with some variation like "Circle One", "Circle Two", etc and the log only picked up "Circle" from the name to report in the error logging, so it took me a while to pinpoint.
FIX: I renamed each circle object without any spaces or special characters and upload was (finally) successful.