SharePoint Sync has stopped with the error
SharePoint Sync relies on the SharePoint APIs provided by Microsoft. These errors are related to the following reasons:
- User Permissions
- Folder or File names contain invalid characters
The user used to connect the SharePoint Sync app must have permissions to the Document Libraries that are being synchronized. If the user permissions to the Document Library is revoked, then the connection to the Document Library is lost and the SharePoint Sync needs to be Re-Activated with a new user or permissions need to be given to the user to access the Document Library.
Folder or File Names
If the folder or file name contains invalid characters as defined by SharePoint, the sync will not work. For information on invalid folders and file names, please refer to the article: Invalid file names and file types in OneDrive, OneDrive for Business, and SharePoint