Can't upload image with mime-type "application/octet-stream" in Symfony2

Question

Let me tell about the problem. I have a form which is called «Image». It contains a field called «file» and it is checked as Image implementation. Here is a part of validation.yml:

noxaeterna\MainBundle\Model\Image:
constraints:
    - Propel\PropelBundle\Validator\Constraints\UniqueObject:
        fields: hash
        message: "Такое изображение уже существует."
properties:
    name:
        - NotBlank:
            message: "Имя изображения не задано."
        - Length:
            max: 255
            maxMessage: "Длина названия не должна превышать {{ limit }} символов."
    file:
        - NotBlank:
            message: "Изображение не загружено"
        - Image:
            maxSize: 20M
            mimeTypes: ["image/jpeg", "image/gif", "image/png", "image/x-png", "image/x-citrix-png", "image/x-citrix-jpeg", "image/pjpeg"]
            minWidth: 1
            minHeight: 1
            minWidthMessage: "Изображение должно быть не менее {{ limit }} пикселей в ширину."
            minHeightMessage: "Изображение должно быть не менее {{ limit }} пикселей в высоту."
            sizeNotDetectedMessage: "Недопустимый формат изображения: не удалось определить размеры."
            mimeTypesMessage: "Недопустимый формат изображения."
            maxSizeMessage: "Файл слишком большой ({{ size }} байт). Размер не должен превышать {{ limit }}."
            uploadIniSizeErrorMessage: "Файл слишком большой ({{ size }} байт). Размер не должен превышать {{ limit }}."
            uploadFormSizeErrorMessage: "Файл слишком большой ({{ size }} байт). Размер не должен превышать {{ limit }}."
            uploadErrorMessage: "Ошибка загрузки изображения."

So what is the problem? When I try to upload some images which have mime-type «application/octet-stream» and have normal extension like .jpg or .png I see an error which tells me that an image has invalid size. Then I try to display the object (an implementation) of «Image» through var_dump() and I see that the «size» field is 0 (it's why the error of invalid size is displayed).

So what I have do with such images to determine their size and download them successfully (I must say that with one of allowed mime-type it works pretty good)?

P.S. I'm sorry about my bad English skill. And as ever I will be thankfull for any answer!

There is new information!. All files which bigger than several megabytes are sent with «application/octet-stream» mime-type.

Answer 1

I add my comment which solved it as an answer so the question will have an answer:

There is new information!. All files which bigger than several megabytes are sent with «application/octet-stream» mime-type.

The problem is that either post_max_size or upload_max_filesize in your php.ini is limiting the size of the upload.