Retain signature files and db images while migrating in rhodes rhomobile

Question

I am using rhodes version 3.4.2, RMS 2.2.1.13 for building an application. What I want is, when I am migrating to a newer build with some data migrations, I would like to keep all the image files and signature files from the previous build to be present. The image files and signature files are being stored in the root directory of the app, and not the default db-files folder for rhomobile. Right now, when I am trying to upload an image which was there in previous build from a new build, I get the following error: Rho::AsyncHttp.upload_file: finished with error 26 failed to open/read local data from file.

Any Suggestion anyone?

Update with code:

     result = Rho::AsyncHttp.upload_file(
    :url => url,
    :ssl_verify_peer => false,
    :multipart => [
      {
        :filename => filePath,
        :name => imageValuesJSON,
        :content_type => imageHeader
      },
      {
        :body => "",
        :name => imageValuesJSON,
        :content_type => imageHeader
      }
    ]
    )