iOS Firebase can't upload mp4 file

Question

I'm trying to upload mp4 file to Firebase, but I'm getting this response:

Error Domain=FIRStorageErrorDomain Code=-13000 "An unknown error occurred, please check the server response." UserInfo={object=video/viedo.mp4, bucket=********.appspot.com, ResponseBody=Can not finalize upload. Current size is 1385472. Expected final size is 1596602.

I don't have any problems with uploading mov files. Can this be connected with fact that before I upload my mp4 file, I create it from mov file programmatically as in MOV to Mp4 video conversion iPhone Programmatically using AVURLAsset (conversion is ok as I watch file using AVPlayer) ?

Edit: code for function that create mp4 file from mov file

private func encodeVideo(videoURL: URL, completion: @escaping (_ url: URL?) -> ()) {
    let avAsset = AVURLAsset(url: videoURL, options: nil)

    //Create Export session
    exportSession = AVAssetExportSession(asset: avAsset, presetName: AVAssetExportPresetPassthrough)
    if exportSession == nil {
        return
    }

    let documentsDirectory2 = FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask)[0]
    let filePath = documentsDirectory2.appendingPathComponent("rendered-Video.mp4")

    deleteFile(filePath: filePath)

    exportSession!.outputURL = filePath
    exportSession!.outputFileType = AVFileTypeMPEG4
    exportSession!.shouldOptimizeForNetworkUse = true
    let start = CMTimeMakeWithSeconds(0.0, 0)
    let range = CMTimeRangeMake(start, avAsset.duration)
    exportSession!.timeRange = range

    exportSession!.exportAsynchronously(completionHandler: {() -> Void in
        switch self.exportSession!.status {
        case .failed:
            completion(nil)
            print("%@",self.exportSession!.error ?? "error saving mp4")
        case .cancelled:
            completion(nil)
            print("Export canceled")
        case .completed:
            completion(filePath)
        default:
            completion(nil)
            break
        }
    })

}

I also sometimes get respone

ResponseBody=Can not finalize upload. Current size is 1854819. Expected final size is 1626331.