SharePoint - Troubleshoot / Help 404 error in SharePoint
Troubleshoot steps if you are getting 404 error for the site collection and central admin is loading properly. 404 generally occurs when your request is hitting the server and server is unable to find/servers your requested page.
- Make sure SharePoint services are running, restart IIS web sites have started, IIS application pools have started and Database are up
- Check ping is receiving reply from network.
- Try accessing the site by server name with full domain and port number.
- Check the Alternate Access Mapping is correctly configured. IIS can handle the connection to the root site, but without this information added, SharePoint cannot properly handle the requests to your other site collections.
- Check your permission level in the site collection or farm and Database.
- Check the http://ServerURL/_layouts/settings.aspx is loading properly. Come times landing page may have error.
- Check the authentication is enabled in the IIS for windows and default logins.
- Check the Firewall port is open to accept request at 80 port. Open firewall settings. Then search for something like - Allow program or feature to allow through firewall. If in the list World Wide Web services (HTTP) is unchecked, check it and restart the system
- Check the HOST file entry for the name/ URL / typos
- Check the bindings in the IIS for the port listener.Make sure the default site is stopped. If you see bindings that look like the following:
ID 1: Bindings: *:80
ID 2: Bindings: www.yoursite.com:80
- Check the Event Viewer log - this will help for most of the issues debugging.
- Check the ULS log is any authentication is failing inside. Some times bin folder or app folder may be locked down.
If this issues occurs intermittently then probably you need to check this article for remounting DB.