This guide will show you how to resolve the error
Error - The specified path, file name, or both are too long.
The fully qualified file name must be less than 260 characters, and the directory name must be less than 248 characters.
Which is caused by mod data with folder structure paths being 260 characters or greater.
On your Game Panel.
For steps 1 and 2, refer to the image below.
1. Open "Actions" tab.
2. Click "Cleanup Mod Data".
3. Let it finish, then close the window.