Hello, I am new to Ignition and SQL and encountered the same error as above.
In Ignition>Databases>Connections: Username and password are correct; Connect URL is set to the correct server and valid, Extra Connections Properties is valid with the correct database name.
I'll add, as mentioned in another post, under Extra Connection Properties I followed my databaseName with the below and received this error:
databaseName=insertedmydatabase; integratedSecurity=true; encrypt=false;
The original post I split this from (not the same one you just linked) is not actually the same error message, you shouldn't copy its advice.
Your error message says the login just straight up failed. You have the wrong username/password or that user doesn't have permissions to access this schema/db, or perhaps isn't allowed via TCP vs named pipes, etc...
