Параметр EntityParameter "<var>X</var>" должен иметь значение, из которого можно вывести тип DbType, либо поддерживаемый тип DbType необходимо установить как значение свойства EntityParameter.DbType.

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The EntityParameter '<var>X</var>' must have a value from which the DbType can be inferred, or a supported DbType must be set as the value of the EntityParameter.DbType property.

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