If you have your Banktivity file stored on an external drive, DropBox, Google Drive, etc., you could be presented with a saving error:

To avoid this error, you will need to move your Banktivity file locally before attempting to upgrade to Banktivity 9.
If you want to share your Banktivity document on more than one device, we recommend using Banktivity’s Cloud Sync feature. In some cases, storing files externally can lead to file corruption.