This site has exceeded its maximum storage limit.Error while uploading file to document library - SharePoint
Issue: Unable to upload files to SharePoint document library irrespective of the document size. Solution: When you delete items from a SharePoint site, they're sent to the site Recycle Bin. When you delete items from a site Recycle Bin, they're sent to the site collection Recycle Bin. A SharePoint site collection administrator can view and restore deleted items from the site collection Recycle Bin to their original locations. If an item is deleted from the site collection Recycle Bin, or it exceeds the retention time, it is permanently deleted. 1. Click the gear icon and go to the "Site Settings" page. 2. Under the Site Collection Administration, click on "Recycle bin". 3. Delete the unwanted files.