It doesn't fail for me using my test version of Calibre Companion.
To make any progress on this I'll need:
- What OS and version are you using?
- If Linux, are you using a distro version or the official calibre binaries?
- A complete calibre debug log showing the connection from start to end.
One thing you can try is to remove the device booklist cache file in case it has become corrupted. It is named "device_drivers_SMART_DEVICE_APP.py.json" and is located in your calibre configuration folder. The next connect probably will take a while, but might work.