Entity Framework: DefiningQuery error <p>I have a Junction table with clustered index </p> <pre><code>CREATE TABLE [dbo].[MeetingTags] ( [MeetingId] INT NOT NULL, [TagId] INT NOT NULL, CONSTRAINT [FK_MeetingTags_Tags] FOREIGN KEY ([MeetingId]) REFERENCES [dbo].[Meetings] ([Id]), CONSTRAINT [FK_Tags_MeetingTags] FOREIGN KEY ([TagId]) REFERENCES [dbo].[Tags] ([Id]) ); GO CREATE CLUSTERED INDEX [cdxMeetingTags] ON [dbo].[MeetingTags]([MeetingId] ASC, [TagId] ASC); </code></pre> <p>Obviously, it has common field of the table Meetings and Tags so that I can add record on it by this way</p> <pre><code>var tag= new Tag() { Title = "Meeting Title", }; meeting.Tags.Add(tag); </code></pre> <p>Looks good, however I'm getting this error in <code>Context.SaveChanges()</code> when Inserting new Tags record.</p> <pre><code>Unable to update the EntitySet 'MeetingTags' because it has a DefiningQuery and no &lt;InsertFunction&gt; element exists in the &lt;ModificationFunctionMapping&gt; element to support the current operation </code></pre> <p>Tags has Primary Key.</p> <p>I think putting a Primary Key in the <code>MeetingTags</code> is not possible as it will break the Many-to-Many relationship of Meeting and Tags in the EF, and it will also add <code>Meeting.MeetingTags.Tags</code> in the syntax instead of just <code>Meeting.Tags</code></p> <p>Any workaround on this?</p>