You may see the following errors in Google Drive:
An unknown error has occurred: Restart Google Drive sync.
An unknown issue occurred and Google Drive needs to quit: Restart Google Drive sync.
Authorization failure: You no longer have permission to view the file. Contact the owner.
Connection failure: Check your Internet connection. Click Retry all or restart Google Drive sync.
Google Drive quits unexpectedly: Reinstall Google Drive.
The Google Drive server encountered an error: Click Retry all.
This file is a link to an online Google document. It cannot be changed. You can only change Google documents when online. Make a copy of the original document online and select it for syncing.
The file on your computer is missing: Restart Google Drive sync.
This file points to an invalid online Google document: The original file is no longer in Google Drive. Remove from the folder on your computer and restart Google Drive sync.
Some files can't be synced: Manually sync files.
Syncing is stuck: Restart Google Drive sync.
Unable to complete sync: Disconnect and reconnect your account.
You do not have enough Google storage for this file. Please buy more storage: Purchase a larger storage plan.
You do not have permission to sync this file: Contact the owner of the file.
You only have permission to view this file, so your changes cannot be synced: Contact the owner of the file and request the ability to edit.
Your Google Drive folder is missing: Locate or replace your missing folder.
more information can be found here: