Problem: When I opened SharePoint 2013 Central Administration site, it returned an error message: HTTP 500 Internal Server Error: The website cannot display the page error message!
Check all required ports are open in Firewall in web & database servers.
Update passwords on IIS Application Pool identities. Make sure they are not stopped or Offline. Update the identity password for “SecurityTokenServiceApplicationPool ” application pool and start it.
In most cases, It’s due to web.config issues! Restore the web.config file from backups or create a dummy web app, copy-paste the web.config file from it.
If your SharePoint Farm account password is changed/expired, Update it with: stsadm -o updatefarmcredentials -userlogin “domain\username” -password “password”
Make sure IIS Web sites are running. SharePoint Timer service is running.
If you are experiencing this issue with the SharePoint 2010 Central Administration site, try re-provision it: How to Re-Provision SharePoint Central Admin Site. Try Running the SharePoint Configuration wizard again – don’t disconnect.
It could be due to SQL Server issues! To Check the database server connectivity issues, SQL Server instance is running in the Database server. Databases are accessible.
Try Re-register Asp.net framework by running :C:\Windows\Microsoft.NET\Framework\<<.NET VERSION >> aspnet_regiis.exe –iru
Make sure your SharePoint setup account is added under the Administrator group of the server(s).
If you get Event ID 8305 with an error message “An exception occurred when trying to establish endpoint for context. An error occurred loading a configuration file. Either a required impersonation level was not provided, or the provided impersonation level is invalid.”, Here is the fix: Go to Start >> Administrative tools >> Local Security Policy >> Local Policies >> User Right Assignments – Impersonate a client after authentication properties >> Add the Application Pool account >> Restart the Server