I encountered the same issue. The root cause is that the external hard drive was unable to write to in Ubuntu for some unknown reason. I fix the problem by running sudo ntfsfix /dev/sdc2 according to [here](https://askubuntu.com/questions/93109/cant…
No worries. I solved the problem by replacing zotero.sqlite by its backup zotero.sqlite.bak (and of course rename it). Changes to zotero in the last two days were lost, but it is better than a ruined lib.
I removed the prefs.js and restarted zotero, it still gets stuck at loading items, also showing message box "Better Bibtex: Initializing \\ Waiting for Zotero database". Is there other approach to fix this issue? Such breakdown always happen just be…