Architectures and techniques for uploading virtual machine (VM) images to a network-accessible computing platform from a client device while simultaneously performing error detection of the VM images at the client device. One technique can include transmitting a request from the client device to upload VM images. The technique can further include receiving an application from the computing platform and using the application to reconstitute the VM images from a first stream at the client device while performing error detection. The technique also includes using the application to upload the VM images from a second stream at the client device to the computing platform while performing the error detection.