Fail to upload a file

[Geddeon]

postFile method returns error: { message: 'String file not found', code: 404 }. Request parameters are:

{ file: { value: ...file content goes here..., options: { filename: 'en.po' } },
  api_key: REMOVED,
  dev_hash: REMOVED,
  file_format: 'GNU_PO',
  is_keeping_all_strings: 'false',
  locale: 'en',
  timestamp: '1524572026',
  is_allow_translation_same_as_original: 'true' }

And file list is:

{
    "meta": {
        "status": 200,
        "record_count": 2,
        "page_count": 1,
        "next_page": null,
        "prev_page": null,
        "first_page": null,
        "last_page": null
    },
    "data": [{
        "file_name": "en.po",
        "string_count": 193,
        "last_import": {
            "id": 3359952,
            "status": "completed"
        },
        "uploaded_at": "2018-03-20T13:36:50+0000",
        "uploaded_at_timestamp": 1521553010
    }, {
        "file_name": "en.pot",
        "string_count": 219,
        "last_import": {
            "id": 3359782,
            "status": "completed"
        },
        "uploaded_at": "2018-03-20T12:09:45+0000",
        "uploaded_at_timestamp": 1521547785
    }]
}