It further states: Swapping to the Development environment displays detailed information about the error that occurred. The Development environment shouldn't be enabled for deployed applications. It can result in displaying sensitive information from exceptions to end users. For local debugging, enable the Development environment by setting the ASPNETCORE_ENVIRONMENT environment variable to Development and restarting the app.
This is commonly seen if you did not create an SQL Database and/or include the SQL Connection string to the database in your appsettings.json file.
Your appsettings.json should be similar to this:
{
"Logging": {
"LogLevel": {
"Default": "Information",
"Microsoft.AspNetCore": "Warning"
}
},
"ConnectionStrings": {
"SqlServer":
"Data Source=sql2019-001.adaptivewebhosting.com; Initial Catalog=MYDB; User ID=MYDBUSER; Password=MYDBPASSWORD"
},
"AllowedHosts": "*"
}