That's a sync error. You can click on it for details.
[JavaScript Error: "Request timed out"]
In this case, the error might be that your sync requests are timing out. If so, that would likely be a problem with your internet connection, but if you provide a Debug ID (different from a Report ID) for a sync that produces the error we can confirm that.
Upgrade Storage
why this circle is red when I just launched the software？
https://s3.amazonaws.com/zotero.org/images/forums/u15528281/8gmcrgqynvdlk9ustppe.png
the ID of error report is 1293777002