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Database and database schema suddenly out of sync

I have (I think) a very strange problem.
I have a web server running an ASP.NET MVC app querying a SQL Server database. It has all been constructed using code-first approach.
It has been working without problems for a long time, and whenever I have needed e.g. a new column in a table, I have added the needed class to the model in question. Then I have run Add-migration 'Migration_Name', and a script has been generating with the proposed changes, and after running update-database, the changes have been applied to the database. Easy and always working.
Yesterday, without making any changes to the database or the models (and by the way not even updating the web-server) it stopped working.
The database throws an error the moment the web-app tries to access the database
System.Data.SqlClient.SqlException: 'CREATE TABLE permission denied in database 'master'
The content of the database is intact I can see from browsing it from within Visual Studio.
If I run the add-migration command, a script is generated for every single table, column, foreign key etc for the entire database, as if the database did not contain a single one of the classes defined in the models.
So it seems that the database is not in sync with my code first models anymore. I got my IT department to copy the entire database to a test server to try to test what is wrong without messing up the production database, and after trying to run the "strange" migration script by using the update-database command, I get the same error:
CREATE TABLE permission denied in database 'master'
and it shows me that it fails when trying to create the first table in the migration script. This is not surprising, since it already exists in the database. But what is going on - I am at a loss!
So can anyone tell me might have happened here, and more importantly, how to fix it?
All the best
Troels

Code-Based migration not working on Oracle database if username or schema name changed

I want to apply Code-Based Migration if any new Oracle Database connect with application (Windows form application - Entity Framework 6 - C#).
Currently i have generated Migration with specific database and schema i.e. (Database = 'TestDB' | Schema = 'PDBADMIN'). But, in my case schema name will be different each new connection with this application. In short not any schema/username fix for connect new Oracle Database with this application. So, when user want to run application(exe) then Code-Based migration will auto execute but it will throw exception if connected Oracle Database does not have same username or schema name (same as during migration generation time available with specific database).
What i tried from my side.
Through application debug mode i applied same migration with another Oracle database where Schema/Username different i.e.(Schema ='PDBTEST' | Database = 'NewDB') but it throw exception.
Unable to update database to match the current model because there are
pending changes and automatic migration is disabled. Either write the
pending model changes to a code-based migration or enable automatic
migration.
Working Scenario
If i connect my application exe with same schema/username in Oracle then it's works.
Not working Scenario
But not work with another schema/username with new database connection (Database is empty) .
How to resolve this issue ?
Any help would be appreciated.
Thanks!

How do I add columns to database without users losing data when a new version of the application is published?

I have a c# .NET application with a SQLLocalDB database. I have used database first to create the EF6 model. I have added columns to one of the tables using SQL Server Management Studio and then used 'Update model from database' to propagate the changes into my model. When doing this, data on the development PC is unaffected and incorporates the new columns. However, when a different user runs the new version of the application, their existing datafile (.mdf) won't recognise the new columns and crashes with the exception:
System.Data.Entity.Core.EntityCommandExecutionException: An error occurred while executing the command definition. See the inner exception for details. ---> System.Data.SqlClient.SqlException: Invalid column name 'VAT_long_description'
making the user's existing data in that table unreachable. I appreciate that Code First gives the ability to migrate data, but this facility appears not to be available when building the EF model using database first.
My connectionString is:
<add name="PMMEntities" connectionString="metadata=res://*/PMMData.csdl|res://*/PMMData.ssdl|res://*/PMMData.msl;provider=System.Data.SqlClient;provider connection string="data source=(localdb)\v11.0; AttachDBFilename=|DataDirectory|\PMM.mdf; initial catalog=PMM;Integrated security=True;MultipleActiveResultSets=True; App=EntityFramework""providerName="System.Data.EntityClient" />
I want to ensure that when a user installs a new version, their .mdf datafile will adapt to the new database schema without loss of data. It seems the only way to do this is through running a conversion or migration method on startup if the app throws the “Invalid column name” SQL exception. Where can I find the code (or a NuGet package) that will do this?

if you are using MVC , you have two methods to make an update in your models class database. the most easy way to resolve that issue is that you delete the model class related to the database and you import it again into your model folder. don't worry about data, they will still stored in your database. unless you have wrotten some extra object in the model class database, in this case you will waste those extra objects.. it will not affect your storage.

How to make entityFramework asking me before create db;

I want to make Entity Framework showing me message : 'There is no database' (if database not exist) and asking me for create db or not;
i use CodeFirst.

In your 'DbMigrationsConfiguration' class, you should turn off any automatic migrations:
public Configuration()
{
AutomaticMigrationsEnabled = false;
}
Now on bootup, it won't do anything other than throw an DBMigrationException when you first access the database. So, before you access the database, check to see if it exists by using the following:
dbContext.Database.Exists();
You can then ask your questions about server location, etc, followed by creating the database with:
var migrator = new DbMigrator(new Configuration());
migrator.Update();

This isn't something built into Entity Framework, nor does it make sense to build it into Entity Framework, because it is so specific to your particular application that whatever you come up with won't be directly usable in any other application.
You can simply configure EF to not automatically create any database. If connecting to the database fails, check if you can connect to the server. If you can connect to the server, check if the database exists. If the database does not exist, offer to create it.

AutomaticDataLossException thrown after initial migration runs in EF 6 in SQL Server but not MySQL

Background info:
I am about to start a new project written in C# (vs2015) which will be using Entity Framework 6 within its DAL. One of the core requirements is that the system must be able to run against either SQL Server, Azure SQL server, MySQL or Oracle as chosen by the user simply changing the connection string in the web.config.
So prior to the project kick-off I am trying to get more familiar with Entity Framework as I have not used it outside of a few tutorials before.
I have written a small proof of concept app, the purpose of which is to determine how I can use EF to quickly swap a web api to use a different underlying DB. For the PoC I am using SQL Server express v12 and MySQL v5.6, C#, Entity Framework 6 via a code first approach.
I have hit a road block with my PoC, I am seeing different behaviour when running against MySQL compared to when I am running against SQL Server. I am using the following EF context:
<context type="POC.Core.Api.DataAccessLayer.SchoolContext, POC.Core.Api" disableDatabaseInitialization="false">
<databaseInitializer type="System.Data.Entity.MigrateDatabaseToLatestVersion`2[[POC.Core.Api.DataAccessLayer.SchoolContext, POC.Core.Api], [POC.Core.Api.Migrations.Configuration, POC.Core.Api]], EntityFramework"></databaseInitializer>
</context>
I have two migration scripts, one which is the initial creation and another which just adds a property to an object.
I have some test data being created in the seed method in the configuration class which looks like this (:
public Configuration()
{
AutomaticMigrationsEnabled = true;
this.SetSqlGenerator("MySql.Data.MySqlClient", new MySql.Data.Entity.MySqlMigrationSqlGenerator());
}
protected override void Seed(WeldOffice.Core.Api.DataAccessLayer.SchoolContext context)
{
var students = new List<Student>
{
new Student { FirstMidName = "Carson", LastName = "Alexander",
EnrollmentDate = DateTime.Parse("2010-09-01") },
...
};
Both my MySQL and SQL servers do not yet have the database present at all yet.
As I want the user to be able to specify the DB I am relying on in-code methods to create the DB structure etc.
Given this scenario, my understanding is that the following occurs when the db context is first hit when running the app:
Check for existence of the database - it is not present so it will be created.
Check if the initial creation script has been run - it has not so run it.
Check if the add property script has been run - it has not so run it.
Run the seed method to ensure data is present and correct.
In MySQL this all works as expected, the database is created, the tables set up and the data populated. The two migration scripts are listed in the migration table.
In SQL Server, steps 1,2,3 all work and the database is created and the tables set up. The two migration scripts are listed in the migration table. However, step 4 is not run, the Seed method is never hit and instead a AutomaticDataLossException exception is thrown.
If I set AutomaticMigrationDataLossAllowed = true then step 4 also works and everything is as expected. But, I would not really want to have AutomaticMigrationDataLossAllowed set to true and don't see why this is necessary in SQL server but not MySQL. Why is this the case? I feel I am missing something fundamental.
Please keep in mind this is just a proof on concept, in production there will be no seed data anyway, and I would rather a dba create the db via sql scripts etc.