A computer-implemented method that can prevent an upload of a data set upon detection of a modification of the data set. The method includes storing a first portion of a file in a buffer while being in a receiving mode. Upon determining that applying one of a predefined transformation performed to the first portion of an existing data set will result in reproducing a content of the buffer: generating a transformation notification signal; and upon receiving a stop message, stopping the receiving mode which results in using the existing file on the server.