REL // SharePoint 2016, SharePoint 2019 Preview
Example: You create a new hostnamed site collection, and when you try to access it for the first time, you receive an application error in your browser.
Application logs contain truncated and gratuitous amounts of Event ID 5586
–Event ID 5586 //
Unknown SQL Exception 18452 occurred. Additional error information from SQL Server is included below.
Login failed. The login is from an untrusted domain and cannot be used with Windows authentication.–
My run-in was a SQL permissions issue. Somehow in my case, the App_Pool Service Account had no permissions whatsoever after creating the site collection (HNSC).
Solution: Identify the service account used for the App_Pool for this Web_App. Permissions in SQL should be: db_creator, public, security_admin
Be kind, be safe and have an outstanding day!