C# – The mapping of CLR type to EDM type is ambiguous because multiple CLR types match the EDM

I've found a work-around. It's a very obvious work-around that is non-ideal, but I think I'm going to call it good enough for us until EF5 comes out to fix this.

Short Answer: Just rename one or both of the ambigous entities Like: 2x Person are renamed to: Personal_Person and Work_Person based on a PersonalContext and a WorkContext.

Long Answer: In our scenario, we're using a DB-first approach (we're rewriting a legacy app with minimal DB changes). Our DB contains hundreds of tables, so rather than using a single EDMX/Context, I'm using multiple EDMX/Contexts (the EDMX has croaked every time I've attempted to add more than half of our tables). However, some tables need to exist in more than one EDMX/Context.

For discussion, let's pretend we have a simple database with the following tables:

• Person
• Family
• Relationship
• Address
• Business
• Employee

Also, for the sake of this discussion, let's assume that ANY table that exists in multiple contexts causes this problem (as I stated in comments to Devart's answer, this is not really true and I don't understand why it sometimes works).

Now let's say we want to create two contexts:

PersonalContext:

• Person
• Family
• Relationship
• Address

WorkContext:

• Person
• Business
• Address
• Employee

In this scenario, both Person and Address will cause our problem. So what we will do in our EDMX mapping is simply rename our entities to Personal_Person/Work_Person and Personal_Address/Work_Address.

As stated, this is very much an obvious work-around that is non-ideal but since EF doesn't take namespacing into account and goes strictly by name (not true identity, simply the name), one option is to put your namespacing inside your name.

Now I'm still debating if I'm going to do it that way or perhaps namespace the name for every entity (Personal_Person, Personal_Family, Personal_Relationship, Personal_Address and Work_Person, Work_Business, Work_Address, and Work_Employee) for both consistency and Intellisense-friendliness (keeping all entities in proper alphabetic order) since really, the namespace belongs before the name instead of after it, but that's a judgement call and not really important to providing a solution to the problem.

I hope this helps!!

Don't use classes with the same unqualified name - EF uses only class names to identify the type mapped in EDMX (namespaces are ignored) - it is a convention to allow mapping classes from different namespaces to single model. The solution for your problem is to name your classes in BLL differently.