Common error messages with Blender : Error message: “HTTP error 401(Unauthorised)”
Go to Blender, user preferences, Add-ons and make sure that the correct API key in the file is correct.
This error often happens when the API Key entered is incorrect.

Common error messages with Cinema 4D : “No curl output file”:
If you received a “no curl output file” error message while using the Augment plugin for Cinema 4D and were unable to upload your model with the plugin.

This problem appears to be linked to the name of the folder containing Cinema 4D.
If your Cinema 4D folder name contains spaces, please replace them by underscores (“_”).
To do so:
1- Make sure the application Cinema 4D is closed.
2-Go to the Maxon Folder containing the “Cinema 4D Rnnn” folder, where nnnn represent the version of your Cinema 4D application.
3- Replace “Cinema 4D Rnnn” by “Cinema_4D_Rnnn”.
4- Launch the application again.
5- Reinstall the Augment plugin. The instruction for installing the plugin here: http://www.augment.com/help/adding-a-3d-model-using-cinema4d-plugin/
6- Try exporting a model with the plugin to verify that the “no curl output file” error message has been solved.