Cloud accounts · Local folder accounts
Why does my Local folder account stop working sometimes?
Short answer: The folder it points at isn't available — an unmounted share, an unplugged drive, or a renamed folder. Reconnect it and click Test connection, or remove the account and add it again at the new location.
Usually because the folder it points at isn't there at that moment — a network share that's unmounted, an external drive that's unplugged, or a folder that was renamed or moved.
Reconnect the share in Finder or plug the drive back in, then click Test connection. If the folder moved for good, remove the Local folder account and add it again pointing at the new location.