Typically "Error Updating Alerts" or "Error Updating Location" is a connection issue.
The first thing to try is to reboot your phone.
If that does not help, verify that the issue is happening on both WiFi and mobile data.
If the issue is occurring on WiFi only, verify that there isn't any kind of DNS setting or firewall that may be blocking the 1Weather app from contacting the server.
If you are on mobile data and see this issue, you may wish to wait a bit and try again.