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Entity Framework core getting error when rerunning the Update Migration

I am working on asp.net core and using EF. I have created database from scratch using EF. Now whenever there are changes in the database, adding new columns, or changing the type etc. Then I run the Update-datebase migration but I am getting an error for having tables and other object in database. Can someone help me what changes would I need to make in order to make the migration successful?
The compile error mentioned that the object already exists. Lets say if I have customer table that is already created in the database, when I run the script again after adding new object or modification, I am getting that error, this does make sense but what is the common practice to deal with the issue?

As described in Migrations Overview after you are evolving your models (adding properties, removing properties, editing them and etc...) you need to update your database schema, in order to do that, you are required to add a new migration.
This can be possible in the one of following ways:
via .NET CLI
dotnet ef migrations add NewMigrationName
via PowerShell
Add-Migration NewMigrationName
After adding a new migration you just need to sync the database by:
Update-Database

EntityFramework EF won't let me re-scaffold

I've done this kind of procedure multiple times successfully, but for the first time, it seems to not work. I want to merge two branches of my application, they have different Code First Migration states. I'm aware of the fact that during development of two versions, the schema changed in both, resulting in a different snapshots, so I need to re-scaffold my merged Migrations to match the database snapshots, basically following this guide, Option 2. In the given Project I have dozens of Migrations and multiple of them were merged and re-scaffolded successfully as described.
So what I'm doing is bringing the database state to the database version before Migration (e.g. Update-Database -targetMigration 201511261243087_BeforeMigration, Step 4 of the Guide) and re-scaffold the merged Migrations in the correct order, so they can re-scaffold the metadata.
When I use the Command Add-Migration 201512170931290_FirstMergedMigration, I get the following error message:
Unable to generate an explicit migration because the following
explicit migrations are pending:
[201512170931290_FirstMergedMigration,
201512140935307_SecondMergedMigration]. Apply the pending explicit
migrations before attempting to generate a new explicit migration.
What? I wasn't expecting this. I'm expecting the command to re-scaffold the existing migration's metadata and update the Schema snapshot. But it's assuming that I want to add a new Migration. The -force flag doesn't help either.
When I follow the recommended step and Update-Database, EF will create a new Migration, called: 201512210931290_201512170931290_FirstMergedMigration. Now THATs really crazy.
I wish there was a separate command to Re-Scaffold Metadata so it would maybe show a clearer error message.
Anybody seen this before?
UPDATE:
See my own answer.

OK so it seems I found the issue here... It seems like the first migration I attempted to re-scaffold, didn't contain any schema changes, because it was only adding Indexes etc. It seems that EF will try to add a new migration if it doesn't detect the change in the given Migration. What I was able to do was to skip that Migration, continue with the next one, which resulted in the expected:
Only the Designer Code for migration
'201512140935307_SecondMergedMigration' was re-scaffolded. To
re-scaffold the entire migration, use the -Force parameter.
I checked the database and the __MigrationHistory looks good, so do the Tables. It would mean less trouble if EF had generated a better error message instead of trying to add a new migration where I clearly was trying to re-scaffold.

Entity Framework 6 Update-Database fails for migration created with -IgnoreChanges

I'm trying to create a DbContext specific to may Domain that has one model class entirely managed by EF, and another that gets mapped to a database view. To ensure EF doesn't try to create this view that already exists, I added just the view to my DbContext and ran the following command:
Add-Migration InitialUnmanaged -IngoreChanges
This creates a Migration with an empty Up and Down, which is exactly what I want. I'm able to update my dev database using this Migration, but whenever I try to add a second Migration that includes my EF-managed model class, I get an error.
Add-Migration Initial
Unable to generate an explicit migration because the following explicit migrations are pending: [201510151553565_InitialUnmanaged]. Apply the pending explicit migrations before attempting to generate a new explicit migration.
The thing is, I've already applied that explicit Migration, and I can see it in my MigrationHistory table.
MigrationId
201510151553565_InitialUnmanaged
Can anyone help me understand why this is happening and how to work around it?

I figured this out.
When I applied the Migration, it put the Migration History table in the same default schema as the model. However, when I tried to roll it back, it was looking for the Migration History in the connected user's schema. Since it wasn't there, it thought the database was at version 0.
I created an OracleDbConfiguration class to specify a custom HistoryContext that specifies the default schema for the Migration History table and I'm able to rollback as expected after applying a Migration.
I verified that I was able to recreate my initial steps and have them work as expected now that I'm explicitly specifying the schema for the Migration History table.

Either delete the migration or just run Update-Database to put entity back in sync. If it is an empty migration your database will not change.

EntityFramework 6.0 CreateDatabaseIfNotExists Code first to create database

What am I doing wrong. I have got a user DbContext setup and working when I originally created the Code-First with powershell it all worked fine.
I implemented Database Initializer as expected on application start.
Database.SetInitializer<UserDbContext>(new CreateDatabaseIfNotExists<UserDbContext>());
Just to test out if it really creates the database I actually dropped the database and now I am stuck the database will not be created. I am using SQL Server 2012, any idea what could be wrong.
The error message I am getting is
System.InvalidOperationException: Migrations is enabled for context 'UserDbContext' but the database does not exist or contains no mapped tables. Use Migrations to create the database and its tables, for example by running the 'Update-Database' command from the Package Manager Console.
I have tried the same from Package Manager console and it is still give me the same message.

Finally figured the solutions, not sure why or what. Changed my Database initializer to MigrateDatabaseToLatestVersion instead of CreateDatabaseIfNotExists worked.
Database.SetInitializer<UserDbContext>(new MigrateDatabaseToLatestVersion<UserDbContext, Configuration>());

Edit:
With your new error message the problem comes from you having migrations enabled and already ran a migration (probably the first creation of the database) and since you dropped the DB the migration history has been lost. If your not using Automatic migrations you can not go in and make changes to the database your self and expect code-first to know about it. Try disabling migrations and re-enabling them to see if that clears out the migration history.
You will need to make a call into the DB either as a read or insert of data for the DB to initially be created. The code you use only tells EF how to deal with a database if one does not exist when it tries to find it. For me I use the method outlined at http://www.codeproject.com/Tips/411288/Ensure-Your-Code-First-DB-is-Always-Initialized

EF Code first - forgot to run "Add-Migration"

I have a Web project which has already been published to the production server. On my development machine, I made some changes on the model class and ran Update-Database without run Add-Migration. I tried to
Update-Database -TargetMigration:"201304020555457_previous_migration"
but I got the error of
Automatic migration was not applied because it would result in data loss.
How to roll back so I can get the full SQL script for applying on the production server?
Update:
I just published the code, start the page in browser, and the database changes (adding columns) were done after it's executed. I don't need to do anything. Does it means it's really not necessary to run Add-Migration every time?

You could undo the changes you made , then run Update-Database.
Then re-make the changes and this time run Add-Migration

If your initializer is MigrateDatabaseToLatestVersion and your configuration has AutomaticMigrationsEnabled set to true then it will update your db without the need for migrations, if it can.
If you really wanted you could only add migrations for changes that your really want documented or you want to modify, You could skip adding simple columns and add migrations for renaming columns for example.
But if i where you I'd keep migrations complete to avoid issues further down the line.