>>>What's GetAll() ?
>>>
>>I got pointed out to this thread
>>http://stackoverflow.com/questions/16530959/entity-framework-5-get-all-method
>>
>>It was
>>

>>IEnumerable <T> GetAll()
>>         {
>>             return _dbSet;
>>        }
>>

>>I've just changed it to IQueryable in the base classes. Now I'll have to fix all application errors due to this change.
>
>Changing to IQueryable should fix your problem - shouldn't think you'll find many side effects

I tried, but I got too many errors :( I had to switch back because I can not resolve all of them by myself.

I'll suggest it on our meeting and hopefully get help to resolve these errors.